State v. Johnson, 542 P.3d 506

Defendant, Peter Johnson, was convicted by a jury of two counts of first-degree sodomy and two counts of first-degree sexual abuse involving his young daughter, M.
During the investigation, M disclosed allegations of sexual abuse to a family friend and to a detective, with some corroborating incriminating statements made by Johnson during a police interview.
At trial, Detective Reynolds improperly vouched for M’s credibility during testimony, referencing her training and experience.
Defense did not object immediately but later moved for a mistrial, arguing the vouching prejudiced the jury in a highly credibility-dependent case.
The trial court denied the mistrial, instead striking the vouching testimony and providing detailed curative and final jury instructions focused on the jury’s exclusive role in credibility determinations.
Johnson appealed, arguing that the curative steps were insufficient and a mistrial was required.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether vouching testimony required a mistrial	Curative action (striking and instruction) was sufficient	Mistrial necessary; curative steps couldn't remove prejudice	Striking & curative instruction were sufficient; affirmed
Whether court should have declared mistrial sua sponte	Not required if curative action is adequate	Court had obligation to act even without defense objection	Not required; court handled vouching properly

State v. Chandler, 360 Or 323 (Or. 2016) (judicially created prohibition on vouching)
State v. Middleton, 294 Or 427 (Or. 1983) (credibility decisions are for the jury, not witnesses)
State v. Black, 364 Or 579 (Or. 2019) (categorical rule against witness credibility opinions)
State v. Sperou, 365 Or 121 (Or. 2019) (vouching by witnesses is prohibited, even indirectly)