## Facts

- Andrea Pia Yates had a documented history of severe mental illness, including depression, psychosis, suicide attempts, and multiple psychiatric hospitalizations.
- Medical professionals warned against additional pregnancies and advised that she not be left alone with her children and that she be continuously supervised.
- After her husband left for work and before her mother-in-law arrived, Yates filled a bathtub and drowned her five children, then called 911 and her husband.
- The State prosecuted Yates for capital murder based on the deaths of three of the children; Yates asserted an insanity defense.
- The State’s only psychiatric expert, Dr. Park Dietz, testified that a *Law & Order* episode aired before the drownings depicting a woman with postpartum depression who drowned her children and was found not guilty by reason of insanity.
- The prosecution referenced the *Law & Order* testimony in examining another witness and again in closing argument to support an inference that Yates planned the crime and understood its wrongfulness.
- After the jury returned a guilty verdict (but before punishment), it was discovered that no such *Law & Order* episode existed; Dietz acknowledged his testimony was mistaken.
- The parties stipulated that Dietz’s testimony about the episode was erroneous; the trial court admitted the stipulation and instructed the jury to treat it as if Dietz had so testified, but denied Yates’s motion for mistrial.
- The jury rejected insanity, convicted Yates, and assessed life imprisonment after answering the “continuing threat” special issue “No.”

## Issues

1. Whether due process was violated because the conviction rested in part on materially false expert testimony.
2. Whether the trial court abused its discretion by denying a mistrial after the falsity of the expert’s *Law & Order* testimony was established.
3. Whether a post-verdict stipulation and instruction could cure any prejudice from the false testimony on the jury’s guilt-phase determination.

## Decision

- The court reversed the conviction and remanded for a new trial.
- The court held there was a reasonable likelihood the false *Law & Order* testimony could have affected the jury’s verdict on insanity.
- The court concluded the trial court abused its discretion in denying a mistrial.
- The court determined the stipulation and instruction, provided after the guilt verdict, did not adequately neutralize the impact of the vivid false testimony.

## Legal Principles

- Due process is violated when a conviction is obtained through false testimony that is material, meaning there is a reasonable likelihood the false evidence could have affected the jury’s judgment.
- Relief does not depend on proving the prosecutor knowingly presented perjury; once material falsity is established, the conviction cannot stand if it may have influenced the verdict.
- When false testimony bears directly on a central contested issue and is stressed by the State, a later curative measure may be insufficient, particularly if it occurs after the jury has decided guilt.

## Conclusion

Because the State’s sole psychiatric expert supplied a dramatic but false factual premise used to rebut the insanity defense, and there was a reasonable likelihood that the testimony influenced the jury’s decision, the conviction was reversed and the case was remanded for a new trial.


Yates v. State, 171 S.W.3d 215 (Tex. App.—Houston [1st Dist.] 2005)