Background
Alex Gerardo Rivera was tried and convicted in San Diego County Superior Court for multiple offenses committed while he was 17 years old, including attempted murder, assault with a deadly weapon, two counts each of assault with a semiautomatic firearm, brandishing a firearm, making a criminal threat, possessing a firearm on school grounds, possession of a firearm by a minor, and prohibited possession of a firearm. As to one incident he was acquitted of attempted murder and a mistrial was declared on the assault charge. The jury found several gun-related and great bodily injury enhancements true, and the court sentenced him to an aggregate term of 48 years in prison.
Because Rivera's age was not an element of any offense except being a minor in possession of a firearm, the prosecution requested a special instruction: "You may not consider the defendant's age for any purpose, other than determining whether he was a minor at the time of the offenses alleged in Counts 2 and 13." Trial counsel agreed to the language and the court gave the instruction.
The only testimony about Rivera's age was his mother's confirmation that he was 17. No witness testified about his mental development, maturity, or teenage brain development. In closing, defense counsel focused on the attempted murder charges, arguing the prosecution failed to prove intent to kill and raising self-defense and heat-of-passion theories. The jury rejected these theories in returning guilty verdicts.
The Court’s Holding
On appeal, Rivera contended the special instruction erroneously and prejudicially misstated the law. Relying on judicial opinions and academic literature on adolescent brain development, he argued his "youth" was relevant to the states of mind required for brandishing, attempted murder, and assault offenses, each of which required assessing the objective reasonableness of his actions. He claimed different results were likely had counsel been able to argue the impact of "all the elements expected to operate on his mind, which was a juvenile mind."
The Court of Appeal assumed without deciding that the instruction was erroneous but found no reasonable probability of a more favorable outcome under the harmless error standard of People v. Watson (1956) 46 Cal.2d 818. Apart from his chronological age, there was no evidentiary basis for counsel to have argued how adolescent brain development affected Rivera's actions: no expert testimony was presented, neither Rivera nor anyone else testified about his thought processes during the crimes, and appellate counsel did not explain how the mere fact that he was 17 could have changed the verdict on any count.
The court distinguished People v. Humphrey (1996) 13 Cal.4th 1073, People v. Ocegueda (2016) 247 Cal.App.4th 1393, and People v. Sotelo-Urena (2016) 4 Cal.App.5th 732, where juries were erroneously barred from considering actual evidence of battered woman's syndrome, mental disabilities, or chronic homelessness. Here there was no evidence supporting arguments about teenage brain development. Because closing argument must rest on evidence in the record, trial counsel could not have made the arguments appellate counsel proposed, and there was no prejudice requiring reversal.
Key Takeaways
- A special instruction barring jurors from considering the defendant's age except to decide whether he was a minor in possession of a firearm does not require reversal when no evidence about adolescent brain development or thought processes was presented at trial.
- Under the Watson harmless error standard, a defendant must show a reasonable probability that an instructional error affected the verdict; the theoretical relevance of youth is insufficient without an evidentiary foundation in the record.
- Closing argument must be based on evidence in the record and reasonable inferences from those facts; counsel cannot argue about adolescent brain development when no witness testified about it.
- Cases finding error where juries were barred from considering evidence of battered woman's syndrome, mental disabilities, or chronic homelessness are distinguishable absent comparable evidence about the defendant's own mental state.
- A defendant who agrees to a special instruction at trial may still challenge it on appeal by claiming it misstated the law, an exception to the general preservation rule, but must still show prejudice.
Why It Matters
The decision reinforces that a defendant's youth, standing alone, is not an evidentiary basis for arguing that adolescent brain development affected the reasonableness of his actions; without expert testimony or other evidence about mental development or thought processes, any instructional error limiting consideration of age is harmless.
The ruling also confirms that while a defendant may challenge an agreed-upon instruction as misstating the law, he must still demonstrate prejudice under Watson; general scientific observations about teenage brain development are insufficient when the trial record contains no evidence connecting them to the defendant's conduct.
Read the full opinion (PDF) · Court docket