Discovery: What and When the Prosecution Must Disclose

Discovery--the information about the other side's case--is supposed to promote fair trials and case settlement. Learn how it works.

By , UCLA Law School Professor

Discovery is the process through which defendants find out about the prosecution's case. For example, through standard discovery procedure, they can:

  • get copies of the arresting officers' reports and statements made by prosecution witnesses, and
  • examine evidence that the prosecution proposes to introduce at trial.

Traditionally, the prosecutor wasn't entitled to information about a defendant's case. But in recent years, discovery has become more of a two-way street. Just as defendants can discover information from prosecutors, so too can prosecutors examine certain evidence in the hands of defendants.

Modern Discovery Policy

Pretrial disclosure of information through discovery can foster settlement and enhance the fairness of trials.

Can prosecutors spring evidence on defendants like they do on TV?

No. In the past, prosecutors could guard evidence from defendants with the same fervor toddlers show in protecting toy trucks and dolls from their siblings. Defendants couldn't force prosecutors to hand over witness statements or even reveal the names of their witnesses. Now the view that advance disclosure will promote fairer trials has taken hold—if defense attorneys know ahead of time what to expect, they can better defend their clients.

Surprise evidence may produce fine drama, but it leads to poor justice. Unlike prosecutors, defendants can't call on police agencies to help them investigate and respond to evidence they find out about for the first time at trial. Thus, every jurisdiction (each state and the federal government) has discovery rules requiring prosecutors to disclose evidence to defendants prior to trial.

Are discovery rules really intended to help defendants at trial?

Not exclusively. Sure, advance disclosure promotes fairer trial outcomes, but it also promotes case settlement, which saves judicial time and resources. If a guilty defendant finds out before trial that the prosecution has a particularly strong case, that defendant will be more likely to plead guilty and save the government the hassle of trying the case. Discovery is likely a significant reason why at least 90% of criminal cases settle before trial.

Issues regarding settlement aside, discovery is intended to help defendants in the sense that prosecutors must hand over certain information that's helpful to the defense.

Does discovery mean that the prosecution has to reveal its case strategy?

No. Discovery rules generally distinguish between raw information like names of witnesses, police reports, and drug or alcohol test results, and attorney theories and strategies. The latter is called "work product." Prosecutors don't have to turn over their work product to defendants—otherwise, it just wouldn't be fair. Lawyers would be incentivized to hide their work or do less of it

Is there a particular period of time prior to trial when the defense is supposed to engage in discovery?

Not really. Prosecutors can't disclose all discovery on the eve of trial, but on the other hand, they don't have to divulge it all way ahead of time. Discovery can unfold gradually. For example, a defendant's attorney might receive a copy of the police report at the first court appearance, but might not receive a prosecution expert's written analysis of blood evidence until shortly before trial.

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