CALCRIM 3500 is the California pattern jury instruction on unanimity. It applies when the prosecution has introduced evidence of more than one act that could satisfy a single charged count, and it tells the jurors they cannot convict unless they all agree the defendant committed at least one of those acts and all agree on which one. The point is to prevent a verdict that looks unanimous on paper but is actually split, with some jurors convicting on one incident and others convicting on a different one.
What the Instruction Says and What It Does
The instruction tells the jury that the People have presented evidence of more than one act to prove the offense, and that jurors “must not find the defendant guilty unless you all agree that the People have proved that the defendant committed at least one of these acts and you all agree on which act [the defendant] committed.”1Justia. CALCRIM No 3500 Unanimity Two things happen in that sentence. Each juror still has to find proof beyond a reasonable doubt, and every juror has to be looking at the same incident when they do.
Without that second requirement, a count supported by two or more discrete acts can produce a fractured verdict. A classic illustration: the defendant is charged with one count of battery, but the evidence describes two separate altercations the same evening. Some jurors might find the first proven; others might rely on the second. The headcount reads twelve, but the jurors never agreed on what the defendant did.
When the Judge Must Give CALCRIM 3500
The California Supreme Court set out the governing rule in People v. Russo (2001) 25 Cal.4th 1124: when the evidence suggests more than one discrete criminal act for a single charge, either the prosecution must elect the act it is relying on, or the court must instruct the jury on unanimity.1Justia. CALCRIM No 3500 Unanimity That “elect or instruct” framework is the backbone of CALCRIM 3500.
The duty to give the instruction belongs to the trial judge, not the defense. Whenever the evidence presents multiple discrete acts that could satisfy the charge, the court must give the instruction on its own motion, with no request required. The obligation traces to People v. Diedrich (1982) 31 Cal.3d 263 and was reaffirmed in Russo.2Justia. CALCRIM No 3500 Unanimity – Section: Bench Notes A judge who sees the ambiguity but stays silent has committed instructional error.
Prosecution Election as the Alternative
The prosecutor can take the instruction off the table by choosing one act and telling the jury to evaluate only that act. Once the election is made, the court does not give CALCRIM 3500 because the risk of a patchwork verdict is gone. Election is a tactical choice. It simplifies the case, but it also commits the prosecution to a single incident. If the evidence on that incident is weaker than the alternatives, the choice can backfire, which is why many prosecutors prefer to present the full picture and rely on the unanimity instruction to keep the jury aligned.
When CALCRIM 3500 Is Not Required
Multiple acts in evidence do not always trigger the instruction. California courts recognize several situations where the jury can deliberate on a single count without it.
Continuous Course of Conduct
When the defendant’s acts are so closely connected in time and circumstances that they amount to a single event, the court treats them as one offense. This exception appears in two forms. The first is when individual acts merge into a single transaction, such as a sustained physical attack. The second is when the charged crime itself describes ongoing behavior over a period of time.2Justia. CALCRIM No 3500 Unanimity – Section: Bench Notes Temporal proximity matters. In Diedrich, the California Supreme Court held that two bribery payments separated in time were not a continuous course of conduct.3Justia Law. People v Diedrich
Substantially Identical Acts
When the acts are so similar that any juror who believed one occurred would inevitably believe the others occurred too, the instruction is unnecessary. The California Supreme Court recognized this in People v. Beardslee (1991) 53 Cal.3d 68, reasoning that there is no real risk of a split verdict when the acts are essentially interchangeable.2Justia. CALCRIM No 3500 Unanimity – Section: Bench Notes This comes up most often when the defendant repeated the same conduct in rapid succession under nearly identical circumstances.
Disagreement on the Defendant’s Role
Jurors do not have to agree on whether the defendant personally committed the crime or helped someone else commit it. As long as they agree on which act is the offense, they can split on whether the defendant was the direct actor or an aider and abettor.2Justia. CALCRIM No 3500 Unanimity – Section: Bench Notes The Russo court explained that a disagreement about how the defendant participated in a single crime is a disagreement about legal theory, not about which act occurred.
Conspiracy Overt Acts
In conspiracy cases, the jury does not need to agree on which specific overt act a co-conspirator performed, or even on which people were part of the conspiracy, so long as the jurors agree a conspiracy existed and the defendant participated in it.2Justia. CALCRIM No 3500 Unanimity – Section: Bench Notes The crime is the agreement; individual acts in furtherance are secondary.
What Happens If the Instruction Was Required and Not Given
When a trial judge fails to give the unanimity instruction in a case that called for it, the conviction is vulnerable on appeal. California treats the omission as state-law instructional error and applies the People v. Watson (1956) 46 Cal.2d 818 standard: reversal is required if it is reasonably probable the defendant would have obtained a better result had the instruction been given.
That standard is more forgiving to the prosecution than the federal constitutional standard, which requires the error to be harmless beyond a reasonable doubt. Under Watson, the appellate court looks at the trial record and asks whether the omission actually mattered. If the evidence overwhelmingly pointed to a single act and the defense was the same whichever act the jury considered, the error is usually harmless. If the evidence of multiple acts was genuinely contested, or the defense ran differently against each act, the error is prejudicial and the conviction falls.
Preservation also matters. A defense attorney who spots the multiple-acts issue at trial can request the instruction on the record, which cleanly preserves the point. If no one requests it, the appellate argument has to lean on the court’s independent duty to instruct, and then on prejudice. Raising it at trial is far cleaner than litigating its absence afterward.
Why the Instruction Matters at Trial
CALCRIM 3500 forces the prosecution to be specific. Once the jury has to agree on one act, the defense can target each act individually and attack weaknesses in identification, timing, or intent for that incident. Without the instruction, the prosecution benefits from volume: jurors can pick whichever incident they personally find most convincing, and the defense has to fight on every front at once.
The instruction also raises the practical bar for conviction. Twelve people agreeing that something criminal happened is easier than twelve people agreeing on which specific act happened and finding it proven beyond a reasonable doubt. In cases with marginal evidence on multiple incidents, that difference can decide the verdict, which is why defense attorneys watch for the multiple-acts issue from the first review of discovery.