No. 866 September 16, 2026 1
IN THE COURT OF APPEALS OF THE
STATE OF OREGON
STATE OF OREGON,
Plaintiff-Respondent,
v.
BILLY LEE OATNEY, JR.,
Defendant-Appellant.
Washington County Circuit Court
18CR70058; A181144
Beth L. Roberts, Judge.
Argued and submitted December 5, 2025.
Richard L. Wolf argued the cause and filed the briefs for
appellant. Also on the opening brief was Richard L. Wolf,
P.C.
Timothy A. Sylwester, Assistant Attorney General,
argued the cause for respondent. Also on the brief were Dan
Rayfield, Attorney General, Benjamin Gutman, Solicitor
General, and Leigh A. Salmon, Assistant Attorney General’
Before Tookey, Presiding Judge, Kamins, Judge, and
Jacquot, Judge.
KAMINS, J.
Reversed and remanded.
2 State v. Oatney
Cite as 353 Or App 1 (2026) 3
KAMINS, J.
Defendant appeals from a judgment of conviction
for first-degree murder on retrial following the grant of
post-conviction relief. He raises seven assignments of error concerning trial proceedings and his immunity agreement
with the state. We reverse and remand based on the third
and fourth assignments of error and therefore address
those assignments first. We then address defendant’s second and seventh assignments of error, as they may arise on
remand. Because defendant’s first, fifth, and sixth assignments of error are unlikely to recur on remand, we do not
address them.1 State v. James, 350 Or App 71, 84, ___ P3d
___ (2026).
We take the historical facts from the Supreme
Court’s decision in an interlocutory appeal in this case, State v. Oatney, 369 Or 555, 558, 508 P3d 482 (2022) (Oatney IV),
and our decision from the post-conviction appeal, Oatney
v. Premo, 275 Or App 185, 219, 369 P3d 387, rev den, 359
Or 847 (2015) (Oatney II). In 1996, the victim, S, was murdered. Defendant entered into an immunity agreement with
the state, in which the state—presumably under the theory
that defendant was not the murderer—promised him use
and derivative use immunity2 in exchange for his account of
1
In defendant’s first assignment of error, he contends that the trial court erred by denying his motion to disqualify the judge assigned to his case, pursuant to ORS 14.250 to 14.270. Because that judge is retired, that ruling is unlikely to recur on remand. See State v. Baughman, 164 Or App 715, 723, 995 P2d 551 (2000), rev dismissed as improvidently allowed, 333 Or 596 (2002) (not addressing assignment of error where “ruling arose in a particular context that is unlikely to recur on remand). In defendant’s fifth assignment of error, he argues that the trial court erred by denying a mistrial based on the prosecutor’s statements in closing argument that defendant’s argument included “lies” and “was the kind of dishonesty that [the jury] heard in this case.” Although those statements are improper, there is no reason to think they will occur on remand. See James, 350 Or App at 84 (not addressing prosecutor’s improper closing argument when reversing on other grounds because “they ought to be avoided or preserved should they occur on remand”). In defendant’s sixth assignment of error, he contends that the trial court erred in denying a motion for a mistrial after the prosecution committed a Brady violation by failing to disclose that a witness was recently shown photographs that that witness used to identify defendant during the original investigation. Because defendant is now aware of the undisclosed evidence, any error is unlikely to recur on remand.
2
When a witness is granted use and derivative use immunity, “the witness is not immune from prosecution, but the state may not use the immunized testimony or any of its direct or indirect fruits.” State v. Soriano, 68 Or App 642, 644 4 State v. Oatney
events. Oatney II, 275 Or App at 209. In his immunized statement, defendant indicated that his codefendant Johnston had
murdered the victim and that defendant’s role was limited to helping Johnston dispose of the victim’s clothing along with the items stolen from her apartment. Oatney IV, 369 Or at
559. At the detectives’ request, defendant gave them permission to play a recording of his statement for Johnston, who
had refused to speak to police about the murder up to that
point. Id. After hearing defendant’s statement that Johnston committed the crime alone, “Johnston’s face turned beet red, and he clenched and shook his fists.” Id. (internal quotation marks omitted). He immediately countered that defendant
was the murderer and asserted in later interviews that he
and defendant had committed the crime together. Id. Both
Johnston and defendant were charged with the aggravated
murder of S. Johnston pleaded guilty, and the state agreed
not to seek the death penalty in exchange for his testimony
at defendant’s trial. Id. at 558. At defendant’s first trial, Johnston repeated his account, which resulted in defendant’s conviction. Id. That conviction was overturned after a postconviction relief proceeding during which the court determined that the state had violated defendant’s use and derivative use agreement by introducing Johnston’s statements
and testimony. Id. at 558, 560-61. In the following retrial, Johnston did not testify, and defendant was again convicted
of first-degree murder. Defendant appeals that judgment.
I. THIRD AND FOURTH ASSIGNMENTS OF ERROR
In defendant’s third assignment of error, he contends that the trial court erred by ruling that Johnston’s
conviction was derived from defendant’s immunized statement and that, if defendant sought to admit the conviction, it would “open the door and allow the State to call
Mr. Johnston to explain that conviction.”
We review the admission of evidence where there
is only one legally correct outcome for legal error. State v. Titus, 328 Or 475, 481-82, 982 P2d 1133 (1999).
n 3, 684 P2d 1220 (1984). In defendant’s agreement, the state promised defendant that “anything you say during the course of this interview and any information that we derive from what you tell us cannot ever be used against you.” Oatney II, 275 Or App at 204 (internal quotation marks omitted).
Cite as 353 Or App 1 (2026) 5
A. Johnston’s Conviction as Derivative Evidence
Generally, to demonstrate that evidence is derived
from an immunized statement, a defendant must prove that
their statement or testimony was made subject to the state’s promise of immunity. The state then must show that its
evidence “is derived from a legitimate source wholly independent” of the immunized statement. Kastigar v. United
States, 406 US 441, 460, 92 S Ct 1653, 32 L Ed 2d 212 (1972). Usually, the trial court holds a hearing—referred to as a
“Kastigar hearing”—in which the state must prove that all
evidence it proposes to use at trial is wholly independent
of the defendant’s immunized statement. Oatney IV, 369
Or at 562. If evidence is not derived from an independent
source, it is considered derivative evidence, meaning that
it was “obtained by use—evidentiary or nonevidentiary—of
the immunized statement.” Oatney II, 275 Or App at 210.
As no party argues to the contrary, we assume without deciding that a conviction can be derived from an immunized statement. As such, the initial question is whether
Johnston’s conviction was derived from defendant’s immunized statement or an independent source. If the conviction is not derived from defendant’s immunized statement,
then its admission is unrelated to the immunity agreement
and cannot open the door to evidence that is subject to the
immunity agreement. See Oatney IV, 369 Or at 570 (determining that arguments based on “admissible, nonderivative evidence” would not open the door to Johnston’s testimony). To be from an independent source, the evidence
must have developed independently, such that the steps
taken to obtain the evidence are untainted by defendant’s
immunized statement. Where the causal chain is tainted by
defendant’s immunized statement, that evidence is derived
from it. See Oatney II, 275 Or App at 219-21 (determining
that the evidence was not derived from an independent
source where the state could not show that, without defendant’s immunized statement, Johnston would have made
the same decision to testify); see also U.S. v. Schmidgall,
25 F3d 1523, 1528, reh’g den, 37 F3d 639 (11th Cir 1994)
(“To establish a wholly independent source, the government
must demonstrate that each step of the investigative chain
6 State v. Oatney
through which the evidence was obtained is untainted.”
(Internal quotation marks omitted.)). Therefore, we consider the causal chain that led to Johnston’s conviction to
determine if the conviction was derived from defendant’s
immunized statement.
Johnston’s conviction stemmed from a guilty plea.
See Blain v. Cain, 327 Or App 584, 590, 536 P3d 623 (2023)
(“[I]n pleading guilty, a defendant admits that they committed the past acts charged in the indictment, and that
admission forms the basis for determining their guilt.”).
That plea agreement was obtained after reading defendant’s
immunized statement to Johnston and was predicated on
Johnston’s agreement to testify against defendant, testimony that echoed the account Johnston gave in response to
hearing defendant’s immunized statement. Oatney II, 275 Or
App at 219. As we have already determined, that testimony
was derived from defendant’s immunized statement. Id. It
follows that because Johnston’s plea agreement formed the
basis of his conviction, and that plea agreement was made
in exchange for his derivative testimony, his conviction is
also derived from defendant’s immunized statement.3 There
is no way to determine whether the government would have
made the same plea offer or whether Johnston would have
accepted the same plea agreement without the motivating
factor of defendant’s immunized statement, and therefore,
the conviction is derived from it.
B. “Opening the Door” in an Immunity Context
As Johnston’s conviction is derived from defendant’s
immunized statement, we next consider whether defendant’s
introduction of that derivative evidence (Johnston’s conviction) would open the door and allow the state to introduce
3
Defendant contends that Johnston’s conviction is not derived from his immunized statement, because if it were, Johnston’s conviction could be overturned based on violations of defendant’s immunity agreement. However, defendant’s immunity agreement was a waiver of defendant’s rights against selfincrimination. The right against self-incrimination under the Fifth Amendment and Article I, section 12, of the Oregon Constitution is a personal right, and therefore, the violation of defendant’s immunity agreement cannot be asserted by another individual. Dept. of Human Services v. F. T. R., 306 Or App 697, 703, 475 P3d 931 (2020); see State v. Makuch/L. A. R., 340 Or 658, 671, 136 P3d 35 (2006) (evidence may be suppressed due to the violation of a personal right only if the person seeking suppression’s rights were violated).
Cite as 353 Or App 1 (2026) 7
additional derivative evidence (Johnston’s testimony).4 The
trial court determined that, because Johnston’s conviction
was derived from defendant’s immunized statement and
supported a conclusion that Johnston murdered S, defendant introducing the conviction would open the door to the
state calling Johnston to explain the conviction. In its written order, the trial court determined: “Defendant may not
present any evidence derived from Defendant’s October 23,
1996, immunized statement or evidence derived from that
statement that suggests Willford Johnston committed the
murder of [S] without opening the door to the state calling
Willford Johnston in this present case.”
“Open the door” is an “inherently vague” phrase,
and we look to context to determine what a trial court
meant by using it. State v. Gutierrez, 304 Or App 431, 439,
466 P3d 75 (2020). Here, the trial court relied on the state’s argument that defendant’s introduction of the derivative
evidence of Johnston’s conviction would “invite further
inquiry” into the nature of the conviction, and therefore,
it would allow the state to introduce Johnston’s testimony.
See State v. Miranda, 309 Or 121, 129, 786 P2d 155 (1990)
(“affirmatively” introducing suppressed evidence “invited
further inquiry” by the state into the suppressed evidence).
Because defendant’s immunity stems from an informal immunity agreement, it is governed by contract principles. See Oatney II, 275 Or App at 204 (“When a person independently enters into an agreement with a prosecutor to
provide information in exchange for some type of immunity,
the resulting informal immunity agreement is governed
by contract principles.”). Contract principles provide for
situations of a “contract omission”—where a contract does
not address a reasonably foreseeable contingency. State v.
King, 361 Or 646, 658, 398 P3d 336 (2017). That issue arises
4
The state additionally argues that defendant’s introduction of Johnston’s conviction could create an independent motivation for Johnston to testify such that the testimony would no longer be derived from defendant’s immunized statement. As the court identified in Oatney IV, whether intervening events could create an independent motivation for Johnston to testify is something the state was free to argue before the trial court, regardless of whether defendant introduced derivative evidence. Oatney IV, 369 Or 576-77. Because the state did not attempt to introduce such evidence of an independent motivation, we are unable to address that argument.
8 State v. Oatney
here, as defendant’s agreement does not address whether
the state has a remedy if defendant introduces derivative
evidence. When a contract omits a term that is essential to
determining the parties’ rights and obligations, such as outlining the state’s options when defendant introduces derivative evidence, courts may supply a default rule or implied
term. King, 361 Or at 658-59. Common practice may support imposing a default rule allowing the state to respond to defendant’s introduction of evidence. See Miranda, 309 Or at 128 (“A defendant’s own inquiry on direct examination into
the contents of otherwise inadmissible statements opens
the door to further inquiry on cross-examination relating to those same statements.”).
However, a contract concerning the waiver of a
criminal defendant’s rights requires special consideration
of due process in addition to usual considerations of common practice and “basic principles of justice.” King, 361 Or at 660, 667; see U.S. v. Alemann, 286 F3d 86, 90 (2d Cir
2002), cert den, 552 US 1187 (2008) (“[d]ue process concerns color our interpretation of a contract involving [a] defendant’s constitutional rights” like an immunity agreement);
Dorsciak v. Gladden, 246 Or 233, 243-45, 425 P2d 177 (1967)
(due process requires knowing and voluntary waiver of right
against self-incrimination). Consideration of defendant’s
due process rights and the state’s superior bargaining position require that such an expansive waiver cannot be read
into defendant’s immunity agreement. See King, 361 Or at
660 (noting a court may place “the burden of expression on
the party that can better cope with it because of bargaining power and drafting skill” (internal quotation marks omitted)); cf. State v. Lobue, 300 Or App 340, 348 n 1, 453 P3d
929 (2019) (Lagesen, P. J., concurring) (acknowledging “the
generally recognized principle that, in the criminal context, agreements with the government should be strictly construed against the government, given its superior bargaining power and potential due process concerns”). Further, the state’s promise of immunity was the only consideration it
offered in exchange for defendant’s waiver of constitutional rights, and that consideration induced defendant’s waiver.
Cf. Santobello v. New York, 404 US 257, 261-64, 92 S Ct 495, 30 L Ed 2d 427 (1971) (discussing that a prosecutor’s promise Cite as 353 Or App 1 (2026) 9
in a plea agreement “can be said to be part of the inducement or consideration” for the waiver of defendant’s rights
including the right to remain silent, and as such, the “promise must be fulfilled”). Reading the agreement to allow the
state to breach even when defendant did not would affront
the voluntariness of that waiver. See Oatney IV, 369 Or at
570 (“[A]ny potential prejudice to the state is a result of the state’s initial decision to grant defendant use and derivative use immunity. Having made that decision, it would
not be appropriate to permit the state to effectively breach the agreement * * *.”); cf. U.S. v. Jimenez-Bencevi, 788 F3d 7, 16-17 (1st Cir 2015) (court violated defendant’s immunity agreement and due process right by requiring disclosure of
his immunized statement to a witness where the immunity
agreement did not allow for the possibility of opening the
door through the presentation of evidence).
That is not to say there are no limits on what a
defendant may introduce without the state being allowed
to respond. “[I]mmunity from use and derivative use leaves
the witness and the * * * [g]overnment in substantially the
same position as if the witness had claimed his privilege
in the absence of a grant of immunity.” Kastigar, 406 US
at 458-59 (emphasis added) (internal quotation marks omitted). To allow defendant to create a fundamentally misleading impression on a significant issue using evidence derived from the immunized statement would leave the state in a
substantially worse position than if defendant had remained
silent. If defendant were to use Johnston’s conviction to
argue that Johnston alone murdered S, contradicting the
factual basis of Johnston’s plea (that he and defendant murdered S together), that would create such a fundamentally
misleading impression on a significant issue as to make it
truly necessary for the court to open the door to allow the
state to correct that misleading impression. State v. Craine, 271 Or App 101, 111, 349 P3d 628 (2015); see Morris v. State of Oregon, 345 Or App 161, 582 P3d 190 (2025), rev den, 375
Or 67 (2026) (Hellman, J., concurring) (noting defense counsel must abide by their “duty of candor to the court and cannot advance legal or factual positions they know to be false” citing the Rules of Professional Conduct). A clear connection between defendant’s derivative evidence, the misleading
10 State v. Oatney
impression on a significant issue, and how the state’s evidence will rebut that misleading impression is necessary to
ensure that both defendant and the state are left in “substantially the same position” as if defendant had not made
the immunized statement in the first place. Kastigar, 406
US at 458; cf. State v. Johnson, 342 Or 596, 622, 157 P3d
198 (2007), cert den, 552 US 1113 (2008) (the defendant’s
introduction of suppressed evidence opened the door where
that evidence aligned with the defendant’s current theory of the case based on a false inference, clearly creating a misleading impression). Here, it was not clear that the introduction of Johnston’s conviction would create such a misleading impression without further argument from defendant. The
court’s ruling that any evidence, including the conviction,
that “suggests Willford Johnston committed the murder of
[S]” would open the door to Johnston’s testimony was overly
broad. That ruling presumed that such evidence would create
a misleading impression without argument from defendant
to support that presumption. Such a misleading impression
must be likely rather than merely possible to justify allowing the state to breach its agreement. As defendant argued
before the trial court, evidence that Johnston was convicted of S’s murder does not create a misleading impression that
he murdered S without defendant. Therefore, the trial court
erred.
C. Fourth Assignment of Error: Denial of Motion for Mistrial
Based on State’s Improper Argument
In defendant’s fourth assignment of error, he argues
that the trial court erred by denying his motion for a mistrial after the state suggested in closing that Johnston was not involved in S’s murder. We review the denial of a motion for mistrial for abuse of discretion. State v. Smith, 310 Or 1, 24, 791 P2d 836 (1990); State v. Serrano, 355 Or 172, 197,
324 P3d 1274 (2014), cert den, 576 US 1037 (2015). The trial court’s denial constitutes an abuse of discretion if the prosecutor’s remarks denied a defendant a fair trial. Smith, 310 Or at 24.
In closing argument and rebuttal, the state
responded to defendant’s arguments that Johnston had
murdered S by suggesting to the jury—despite Johnston’s
Cite as 353 Or App 1 (2026) 11
conviction for the crime—that Johnston was not involved.5
Defendant contends that those comments were improper,
and the court erred by denying a motion for mistrial.6
A prosecutor’s false or misleading argument violates due process if it rises to the level of denying defendant a fair trial. See State v. Pouncey, 303 Or App 365, 369, 464 P3d 448, rev den, 367 Or 76 (2020) (“[W]e review the trial
court’s denial of [the] defendant’s mistrial motion for an
abuse of discretion, asking whether the prosecutor’s unremedied misstatement so affected the jury’s consideration as
to deny [the] defendant a fair trial.”); see Andrew v. White, 604 US 86, 93, 145 S Ct 75, 220 L Ed 2d 340 (2025) (“[P]
rosecutors’ prejudicial or misleading statements violate due process if they render a trial * * * fundamentally unfair.”).
Prosecutors bear “special ethical considerations,”
including an obligation not to present an argument when
“the prosecutor knows an inference to be false.” See State
v. Strain, 374 Or 783, 791 n 5, 583 P3d 1002 (2026) (listing examples of special ethical considerations for prosecutors
from Standard 3-6.8 of the ABA Criminal Justice Standards
for the Prosecution Function (2017)). Where the state invites the jury to draw an inference that it knows to be false, a
defendant is denied a fair trial, regardless of whether the
evidence before the jury proves it to be false. See State v. Burton, 373 Or 750, 758, 767 n 9, 571 P3d 736 (2025) (noting other courts have relied on the special obligation of prosecutors not to makes false arguments in acknowledging that
“ ‘it is decidedly improper for the government to propound
inferences that it knows to be false, or has very strong
5
The state described Johnston’s “noninvolvement”:
“This defendant, and this defendant alone, based on the evidence that
you’ve heard, is entirely responsible for murdering [S] under the circumstances
that are outlined here * * * * * there’s no evidence at all, again, that Willford
Johnston was involved in this.”
6
Before the trial court, defendant argued that the statements amounted to a due process violation. On appeal, defendant argues the statements were a Napue violation. Napue v. Illinois, 360 US 264, 269, 79 S Ct 1173, 3 L Ed 2d 1217 (1959). However, Napue requires the state not to use false evidence rather than make false arguments, as occurred here. See Tiner v. Premo, 284 Or App 59, 78, 391 P3d 816, rev den, 361 Or 886 (2017) (prosecutor did not commit a Napue violation by making an improper closing argument because “statements an attorney makes during closing argument are not evidence”).
12 State v. Oatney
reason to doubt’ ” (quoting United States v. Blueford, 312 F3d 962, 968 (9th Cir 2002))). Because a prosecutor’s client is the public, they have “a heightened duty of candor to the courts” and should not make statements that they do “not reasonably believe to be true.” Standard 3-1.4 of the ABA Criminal Justice Standards for the Prosecution Function (2021). By
emphasizing “the noninvolvement” of Johnston, the state
improperly invited the jury to draw an inference it knew to
be false—that Johnston was not involved in S’s death.
The state now contends that its argument regarding Johnston’s “noninvolvement” and that “this defendant,
and this defendant alone, based on the evidence that you’ve
heard, is entirely responsible for murdering [S]” did not misrepresent the evidence actually presented and complied with
the requirement that “counsel may not suggest that they are
aware of evidence that was not presented to the jury.” Burton, 373 Or at 761-62. That may be true, but the state strayed
too far in the opposite direction—presenting arguments
antithetical to evidence of which the state was aware and
that was not presented to the jury. The state argues that it was only responding to defendant’s argument that “Johnston
may have murdered the victim while acting alone.” However,
regardless of the motivation, the prosecutor’s argument that “this defendant alone” murdered S, immediately prior to
stating that “there’s no evidence at all, again, that Willford Johnston was involved in this” was plainly contrary to what
the prosecutor knew to be true. See Blueford, 312 F3d at 968 (determining the defendant was denied a fair trial where the prosecutor’s arguments asked the jury to infer facts the prosecutor knew to be false because the prosecutor had specific
evidence contradicting the inference that was not introduced at trial). That argument denied defendant a fair trial, and
therefore, it was an abuse of discretion not to grant defendant’s motion for a mistrial.
Because defendant’s second and seventh assignments of error may recur on remand, we address them below.
II. SECOND ASSIGNMENT OF ERROR
Defendant contends that the prosecutor and trial
court violated his immunity agreement in multiple ways.
Cite as 353 Or App 1 (2026) 13
Defendant’s “informal immunity agreement is governed by
contract principles.” Oatney II, 275 Or App at 204; United
States v. Plummer, 941 F2d 799, 803 (9th Cir 1991). Therefore, we review the court’s factual findings for any evidence, and we review whether the facts establish a violation of the
immunity agreement for legal error. Plummer, 941 F2d at
803; Santoro v. Eagle Crest Estate Homesite Owners Assn.,
319 Or App 793, 798, 512 P3d 828 (2022); Dept. of Education
v. Vantage, 243 Or App 557, 566, 261 P3d 17 (2011).
A. Buden Shifting Regarding Immunity Agreement
Violation
Defendant first argues that the trial court erred by
requiring him to prove breach of the immunity agreement
before requiring the state to prove that its evidence was
not derived from the immunized statement—the showing
required under Kastigar.
In Kastigar, the court considered whether the
government may compel testimony, subject to a grant of
immunity, from a witness who invoked their right against
self-incrimination. The court held that, once a person has
demonstrated that they spoke subject to a state grant of
immunity, the state must meet the “heavy burden” of proving that any evidence it proposes to use to prosecute them
is “derived from legitimate independent sources.” Kastigar,
406 US at 461-62. Defendant argues that the state must
meet that burden here.
Unlike the defendant in Kastigar, defendant here
voluntarily waived his rights against self-incrimination
through his informal immunity agreement. Because his
waiver was voluntary rather than compelled, we look to the
terms of the parties’ agreement to determine its scope.
An informal immunity agreement, like defendant’s, is governed by contract principles. Oatney II, 275
Or at 204. Under contract law, a party must prove breach
by a preponderance of the evidence in order to recover for
a breach of contract claim. Northwest Natural Gas Co. v.
Chase Gardens, Inc., 333 Or 304, 312 n 3, 39 P3d 846 (2002); Currey v. Butcher, 37 Or 380, 390, 61 P 631 (1900). Applying that principle in this case, defendant would bear the burden 14 State v. Oatney
of proving that the state’s evidence breached the agreement
by preponderance of the evidence prior to the court requiring the state to demonstrate that its evidence was derived
from an independent source.
Defendant contends that the prior appeals of this
case suggested that he need not prove breach before the state is required to demonstrate an independent source. However,
the prior cases focused solely on issues concerning the state’s burden. Oatney II, 275 Or at 217 (“If trial counsel had raised [the issue of Johnston’s testimony being derived from defendant’s immunized statement], the state would have had the
burden of showing that Johnston’s statements and testimony
were derived from a legitimate source * * *.” (Internal quotation marks omitted.)); Oatney IV, 369 Or at 573-74 (explaining how Kastigar burden applies to witness testimony). As
such, they do not examine whether defendant was required
to first prove breach before applying that burden.
Typically, we “look to Kastigar and its progeny in
understanding use and derivative use immunity in the
context of this particular case.” Oatney IV, 369 Or at 573.
Other courts applying Kastigar to informal immunity
agreements have required a defendant to demonstrate a
breach. Specifically, before requiring the government to
meet its burden, “[a]s in any contract case, [the defendant] must show that the contract was breached by a preponderance of the evidence.” U.S. v. Mendoza, 78 F3d 460, 464-65
(9th Cir 1996); see U.S. v. Hemphill, 514 F3d 1350, 1354 (DC Cir 2008) (“the defendant has the burden to prove any government breach” of an informal immunity agreement, and
what is considered a breach is determined by the terms of
the agreement).7 Here, because the agreement requires the
7
Several other courts have assumed Kastigar applied without considering whether the nature of the agreement required a defendant to meet an additional burden. See U.S. v. Palumbo, 897 F2d 245, 249 (7th Cir 1990) (determining that because the parties did not dispute that the defendant had received informal use and derivative use immunity, Kastigar was triggered and the government bore the burden of proving all evidence it proposed to use was derived from legitimate independent sources including evidence used to obtain the indictment); United States v. Williams, 809 F2d 1072, 1083 (5th Cir 1987) (explaining that because the defendant cooperated with the government under an immunity agreement and was indicted on charges related to that investigation, the government bore the burden of proving an independent source for all evidence introduced). Cite as 353 Or App 1 (2026) 15
state to provide use and derivative use immunity, defendant
proves breach by showing that the state made use or derivative use of his immunized statement.
Based on contract principles, our prior consideration of the case, and Kastigar and its progeny, the court did not err in placing the burden on defendant to demonstrate a
breach prior to shifting the burden to the state.
B. Prosecutors, Witnesses, and Evidence in Closing
Statement Not Derived from Defendant’s Statement
Defendant next contends that the trial court erred
in allowing prosecutors and witnesses who were exposed to
the immunized testimony to work on the case, to present the
case to a grand jury, and to testify at trial.8 Defendant also argues that derivative evidence was used during closing
argument. Whether facts establish a violation of an immunity agreement is a question of law. Plummer, 941 F2d at
802.
1. Prosecutors
Defendant contends that the prosecutors’ exposure
to both the immunized statement and derivative information tainted their preparation of the case and violated defendant’s immunity agreement. Specifically, defendant argues
that prosecutors are prohibited from using immunized
statements in any prosecutorial decision-making and that
safeguards like a filter or taint team to protect against uses of immunized and derivative information were necessary to
prevent that type of violation of the immunity agreement.
A prosecutor’s exposure to an immunized statement
can influence prosecutorial decision-making short of introducing tainted evidence. State v. Soriano, 68 Or App 642,
663, 684 P2d 1220 (1984). For example, exposure can impact
a prosecutor’s decision on whether to pursue a line of investigation, whether to prosecute at all, or whether to offer a plea bargain. It can also illuminate the significance of other
8
The trial court required defendant to prove breach by a preponderance of the evidence in considering the admissibility of the evidence related to the grand jury proceeding and subsequent Kastigar hearing.
16 State v. Oatney
evidence or impact trial strategy. Id. The state’s promise
protects against such uses. Thus, it requires that the state’s pre-trial and trial strategy and the scope of its investigation be based on independent sources. See U. S. v. Danielson, 325 F3d 1054, 1074 (9th Cir 2003) (requiring the government to
prove its trial strategy was derived from legitimate independent sources to meet its burden under Kastigar for use and
derivative use immunity); cf. Oatney II, 275 Or App at 209
(evidence derived from the immunized statement includes
“any evidence obtained by use—evidentiary or nonevidentiary—of the immunized statement”).
Therefore, we agree with defendant that prosecutors are prohibited from using immunized statements in
prosecutorial decision-making. However, addressing that
taint does not necessarily require, as defendant posits, a
taint team or that a prosecutor have no knowledge of the
immunized statement. Instead, the prosecution must prove
that “its proposed evidence is without taint” and that “its
case is unaffected by prohibited non-evidentiary uses.”
Soriano, 68 Or App at 664; Oatney II, 275 Or App at 209.
That burden may be “virtually undischargeable” in some
cases, United States v. McDaniel, 482 F2d 305, 312 (8th Cir
1973), but here, the state successfully discharged it.
The trial court evaluated the prosecutorial decisionmaking, requiring the state to prove that it had “ independent leads in which to prosecute” and that it had not “used
that testimony against defendant.” Applying that standard,
and relying on the declarations of the two prosecutors, the
court determined that “[a]s a question of fact, I think for
the Court to decide and given the facts, I’m not finding that there’s a need to remove this team from the prosecution at
this time,” concluding that defendant had not met his burden to prove breach.
The record supports the trial court’s factual finding that the prosecutors had independent leads. One prosecutor declared that he reviewed defendant’s immunized
statement “in order to make certain that the tainted information or information derived from the tainted information
was not used [before the] grand jury and will not be used in trial” and had developed his conclusions about trial strategy Cite as 353 Or App 1 (2026) 17
based on “early police reports leading up to the immunized
statement.” The other prosecutor averred that he had read
summaries of defendant and Johnston’s statements and the
Oatney II opinion but had otherwise “chosen not to learn
the details of defendant’s immunized statement.” That minimal exposure, or exposure in order to ensure derivative
evidence is not used, does not violate defendant’s immunity
agreement.
2. Witnesses
Defendant also challenges the admission of testimony by Travis Hampton, one of two original lead detectives, and Kevin Winfield, an investigator during the
original trial and retrial, arguing that their exposure to
defendant’s statement tainted their testimony before the
grand jury and indicated that they made non-evidentiary
use of defendant’s statement during their investigation,
including using derived evidence while interviewing other
witnesses. Defendant also argues that the admission of testimony by Josh Galbraith, a former neighbor of defendant,
violated defendant’s immunity agreement because that witness came forward after defendant’s arrest (which itself was based on Johnston’s statement). We defer to the trial court’s credibility finding and are bound by the trial court’s factual findings if there is evidence in the record to support them. A. J. T. v. Croft, 311 Or App 574, 577, 492 P3d 778 (2021)
(“[W]e generally defer to the trial court for its assessment of credibility.”). In immunity cases, a credibility finding
includes both a witness’s truthfulness and whether a witness “is truly able to isolate” the factors that led to his testimony and investigative path. Oatney IV, 369 Or at 575. Whether
the facts establish a violation of an immunity agreement is
a question of law, which we review for legal error. Plummer, 941 F2d at 802; Santoro, 319 Or App at 798.
Generally, if a witness is exposed to immunized
information, a witness’s testimony must be excluded if the
immunized statement shaped, altered, or affected the information provided, even if the witness is testifying from personal knowledge. Oatney IV, 369 Or at 574. “Generalized
denials that the exposure shaped, altered or affected the
18 State v. Oatney
content of a witness’s subsequent testimony are insufficient.” Id. at 575.
Hampton had a police report summarizing the
immunized statement and the immunized statement
itself in a binder before him both when he testified before
the grand jury and when he testified during the Kastigar
hearing. While he did not refer to the binder during his
grand jury testimony, he did use documents in the binder
“to refresh [his] memory” during the Kastigar hearing.
Defendant argues that that use of the immunized statement
is prohibited. See Aiken v. U.S., 956 A2d 33, 45 (DC 2008)
(Aiken I) (“[A] prohibited use occurs if a witness’s recollection is refreshed by exposure to the defendant’s immunized
testimony * * *.” (Internal quotation marks and citations
omitted.)). Defendant also contends that the admission of
Winfield’s testimony violated defendant’s immunity agreement, due to Winfield’s exposure to defendant and Johnston’s statement shaping his investigation and his opinion that S
was raped. The trial court credited Hampton and Winfield’s
testimony that the investigation did not rely on anything
derived from defendant’s statement and that the evidence
presented to the grand jury “was not tainted by the immunized statement of [defendant].” Those findings are supported by the record.
The immunized statement’s availability to a witness during his grand jury testimony to refresh a witness
as to its contents is not the equivalent of the witness using it to refresh his recollection as to the investigation during the grand jury proceeding. Nor is using it to refresh his
memory during a subsequent Kastigar hearing the equivalent of using it to refresh his memory during the grand
jury proceeding itself. Here, Hampton prepared the binder
in order to separate references to the immunized statement
that occurred during the investigation. His testimony indicated wholly independent sources, like interviews conducted
prior to the immunized statement, for the included information. That does not indicate that his testimony or investigation was shaped, altered, or affected by the exposure; to
the contrary, it reflects an effort to segregate independently Cite as 353 Or App 1 (2026) 19
obtained evidence from that derived from the immunized
statement.
Similarly, Winfield took steps to limit his exposure to defendant’s immunized statement during the current investigation and provided independent sources for his
investigative decisions. Defendant contends that Winfield’s
conclusion that S was raped was derived from defendant’s
immunized statement. However, Winfield testified that that
opinion was supported by evidence other than his exposure
to defendant’s immunized statement; indeed, that evidence
predated defendant’s immunized statement and included
defendant’s description of his interactions with S, another
witness’s description of defendant’s interactions with S,
and the condition of S’s body. Defendant further contends
that Winfield’s testimony indicated witnesses were tainted
because he stated that it “would be natural” after obtaining defendant’s statement to follow up with witnesses. However,
Winfield did not recall, nor were there indications in reports, that witnesses had been exposed to defendant’s statement
or derived evidence. That account does not indicate that
the investigation or any witnesses’ testimony was shaped,
altered, or affected in such a manner as to create a violation of defendant’s immunity agreement.
Defendant also contends that the court erred by
admitting testimony of Josh Galbraith because he came
forward only after defendant’s arrest following Johnston’s
statement. The trial court determined that Galbraith’s
testimony was obtained from a wholly independent source
because, although defendant’s arrest was reported in the
media, that “was not state action that violated the immunity agreement.” The record does not indicate that Galbraith was motivated to testify based on derivative evidence or that his testimony was shaped, altered, or affected by derivative evidence. The trial court did not err in declining defendant’s invitation to infer based on timing of media reports alone
that the witness was motivated by derivative evidence.
Oatney IV, 369 Or at 576 (explaining that witness testimony
may be derived based on motivation derived from defendant’s immunized statement or because the testimony was
shaped, altered, or affected by the immunized statement).
20 State v. Oatney
3. Use of derivative evidence in closing argument
Defendant also contends that the prosecutor’s discussion of S’s sexual assault in closing argument violated
defendant’s immunity agreement.9 Defendant argues that
because Johnston’s testimony, which was “derived from
[defendant]’s immunized statement,” was the “only direct
evidence of [defendant]’s involvement in the sexual assault
and murder of the victim,” Oatney II, 275 Or App at 222-23, the reference to sexual assault violated defendant’s
immunity agreement. However, the prosecutor’s statement
was based on independent grounds, including defendant’s
descriptions of his sexual interest in S. Further, during the retrial, a witness testified that defendant mouthed that he
had sexually assaulted S during the original trial. That
testimony provided an independent source for the prosecutor’s argument. Therefore, it did not violate the immunity
agreement.
C. Inevitable Discovery Doctrine
In defendant’s final argument relating to his second
assignment of error, he contends that the trial court erred
by admitting recorded calls made by Johnston based on the
state’s argument that that evidence would have been inevitably discovered using “proper and predictable investigatory procedures.” Defendant contends that “inevitable discovery”
cannot be used to prove an independent source in an immunity context.
In Oregon, evidence obtained in violation of the
constitutional protections against search and seizure may
nevertheless be admitted if the state can demonstrate that
the evidence would have inevitably been discovered. See
State v. Johnson, 340 Or 319, 326, 131 P3d 173 (2006) (illegally obtained evidence admissible “by proving that ‘such
evidence inevitably would have been discovered, absent the
illegality, by proper and predictable police investigatory procedures’ ” (Internal citation omitted)). Inevitable discovery has not yet been applied to evidence derived from an immunized statement, although its application has been assumed.
9
The state argued in closing: “This was a proceeding that had to do with the rape and murder of [TL’s] daughter.”
Cite as 353 Or App 1 (2026) 21
See Oatney II, 275 Or App at 20 n 5 (“Because petitioner has not raised the issue, we assume that the inevitable discovery doctrine can properly apply to a statement, rather than
physical evidence.”).
Inevitable discovery in an immunity context raises
different concerns than those raised by its application to illegally obtained evidence. See United States v. Martinez, 81 F Supp 3d 1046, 1060 n 14 (D Colo 2015) (“the concerns presented by immunized testimony are unique” compared to
application of inevitable discovery doctrine in other contexts). In search-and-seizure cases or Miranda cases, courts must
balance the cost of excluding illegally obtained evidence with the need to deter future violations of constitutional rights, in regard to the federal constitution, and vindicate a personal right to be free from unlawful searches and seizures, in regard to the Oregon constitution. Id.; State v. Smith, 327 Or 366, 379, 963 P2d 642 (1998). Both of those approaches—the
federal deterrence-based approach and the Oregon rightsbased approach—balance the cost of exclusion with the value
of addressing a constitutional violation that has already
occurred. In contrast, immunized testimony is acquired
legally—without a violation of constitutional rights—by “a
conscious prosecutorial choice, taken after careful consideration and with full knowledge of its results.” Soriano, 68 Or App at 663. Any violation only occurs when the evidence is
presented at trial, not when it was obtained. Martinez, 81 F Supp 3d at 1060 n 14. Thus, in the immunity context, the
court must instead balance the societal interest in enforcement of the government’s promise with the cost of excluding
relevant evidence from jury consideration and impeding the
jury’s “truth-finding function.” United States v. Leon, 486 US 897, 898, 104 S Ct 3405, 82 L Ed 2d 677 (1984); State v. Bailey, 356 Or 486, 495, 338 P3d 702 (2014) (“[C]ourts must weigh
the likely social benefits of excluding * * * evidence against the likely costs * * *.” (Internal quotation marks omitted.)).
Like the independent source requirement from
Kastigar, inevitable discovery balances those interests.
Under Kastigar, that balance is struck when the state proves that the evidence is “derived from a legitimate source wholly independent of the compelled testimony.” Kastigar, 406 US
22 State v. Oatney
at 460. That mirrors the independent source doctrine in the
search and seizure context, which permits the introduction
of evidence that would have been “obtained independently
from activities untainted by the initial illegality.” State v. Johnson, 335 Or 511, 519, 73 P3d 282 (2003) (internal quotation marks omitted). The inevitable discovery doctrine, like the independent source doctrine, balances those interests
by ensuring a defendant is not in a worse position than if
they had never made the immunized statement. Cf. Nix v.
Williams, 467 US 431, 443, 104 S Ct 2501, 81 L Ed 2d 377
(1984) (“[T]he interest of society in deterring unlawful police conduct and the public interest in having juries receive all probative evidence of a crime are properly balanced by putting the police in the same, not a worse, position that they would have been in if no police error or misconduct had
occurred.”). That the evidence inevitably would have been
discovered is sufficient to show the evidence is “derived from a legitimate source wholly independent of the compelled testimony.” Kastigar, 406 US at 460.
III. SEVENTH ASSIGNMENT OF ERROR
Finally, defendant contends that the trial court
erred by admitting testimony by MB, S’s sister, and her
cousin, CL, that during defendant’s initial 1998 trial, he
had mouthed the words “I fucked her” to MB and her father.
Defendant argues three theories as to why the trial court
erred: 1) the testimony was derived from his immunized
statement; 2) the testimony was unreliable and therefore
should not have been admitted under OEC 104(1); and 3) the
evidence was unfairly prejudicial under OEC 403. The trial
court did not err by admitting MB’s and CL’s testimony.
A. The evidence was not derived from defendant’s immunized statement.
Defendant argues that, because Johnston’s testimony derived from the immunized statement was “the only
direct evidence of [defendant’s] involvement in the sexual
assault and murder of the victim,” presented during the original trial and the witnesses had been exposed to that testimony in the original trial, their testimony must have been
shaped by it. Oatney II, 275 Or App at 223. However, MB and
Cite as 353 Or App 1 (2026) 23
CL’s testimony rests on independent grounds—defendant’s
actions during the 1998 trial—not defendant’s immunized
statement. See id. at 217 (witness’s testimony admissible
if “derived from a legitimate source wholly independent of
petitioner’s immunized statement”). Its admission therefore
did not violate defendant’s immunity agreement.
B. The evidence was admissible under OEC 104(1).
We review the trial court’s ruling under OEC 104(1)
regarding relevance and admissibility of evidence for legal
error, “view[ing] the record consistent[ly] with the trial
court’s ruling * * *, accepting reasonable inferences and reasonable credibility choices that the trial judge could have
made.” State v. Carlson, 311 Or 201, 213-214, 808 P2d 1002
(1991).
The preliminary question of fact before the trial
court was whether defendant mouthed those words.
Defendant contends that there was not sufficient evidence
to support a reasonable inference that he had because there
was no objective record of him mouthing the words and lipreading is difficult to do accurately even by an expert lipreader under ideal conditions. However, viewing the record
consistently with the trial court’s ruling, the trial court
could determine by a preponderance of the evidence that
defendant had mouthed those words and choose to admit
MB and CL’s testimony as sufficiently reliable. Specifically, MB, who was in close proximity to defendant at the time of
the incident, testified that she was sure of the words that
she saw, and CL confirmed that MB had told him about
it immediately afterwards. See Carlson, 311 Or at 209 n 9
(“Proof by a preponderance of the evidence means that the
factfinder must believe that the facts asserted are more
probably true than false.” (Internal quotation marks and
brackets omitted.)).
C. The evidence was not unfairly prejudicial.
Defendant also contends that the evidence’s admission was unfairly prejudicial because it would have alerted
the jury to defendant’s previous conviction. Specifically, on redirect, the prosecutor asked CL, “Is it fair to say that you didn’t think you had to talk to your family about this * * * for 24 State v. Oatney
roughly 20 years or so because this defendant wouldn’t have
been on your mind during that time period?” Defendant
contends that that question referenced defendant’s previous trial and conviction in a prejudicial manner—implying
that CL did not discuss the mouthed words with his family
because defendant had been convicted. However, because the
reference was brief and did not mention the prior proceedings, the trial court did not abuse its discretion by admitting the testimony. Titus, 328 Or at 481 (providing standard of
review); cf. State v. Reed, 340 Or App 509, 513, 571 P3d 766, rev den, 374 Or 379 (2025) (singular reference to the defendant’s prior felony conviction that did not include details of the case or the charge was not unduly prejudicial).
IV. CONCLUSION
As explained above, we reverse and remand on the
third and fourth assignments of error. Because defendant’s
immunity agreement is contractual and does not provide
for the prosecution’s use of the immunized statement in
response to defendant “opening the door,” defendant’s introduction of derivative evidence could only open the door to
the state’s use of derivative evidence where that evidence
creates a fundamentally misleading impression on a significant issue, such that further derivative evidence is necessary to correct that misleading impression. The trial court’s denial of a mistrial based on the prosecutor’s argument that was irreconcilable with known, though not introduced, evidence, denied defendant a fair trial.
Reversed and remanded.