What is an Alibi?

An alibi can be an effective defense to a criminal charge, but how do alibis work?

An alibi is evidence showing that a defendant was somewhere other than the scene of a charged crime at the time that the crime occurred. Film and TV characters often pronounce the word "alibi" with a sneer, suggesting that alibi claims are inherently untruthful. In reality, an alibi is a perfectly respectable legal defense. 

Here's how it works: Ellis Ware is charged with robbing a convenience store. Ware offers evidence that he was attending a Kiwanis Club meeting at the time of the robbery. Ware's defense amounts to an alibi. Read on to learn more about alibis. (For in-depth discussion of other common defense strategies in criminal cases, check out Nolo's article Defenses to Criminal Charges.)

Alibis Don't Mean Defendants Must Testify

Defendants may offer an alibi defense without giving up their constitutional right to remain silent. Any witness who can place the defendant at a location other than the scene of the charged crime can provide an alibi.

Let's use the example discussed above as an illustration of how this works. Ellis Ware (who is charged with robbery) chooses not to testify at his trial, fearing that if he testifies the judge will allow the prosecutor to attack his credibility by offering evidence of Ware's prior felony conviction. Ware's defense attorney supports Ware's alibi defense by calling Miriam as a witness to testify that she was with Ware at the Kiwanis Club meeting at the time of the robbery. To bolster the alibi defense, Ware's attorney shows Miriam a photograph depicting her, Ware, and others, and asks Miriam to identify the photo as one that was taken during the meeting. (For more about what happens at trial, see Nolo's articles Criminal Trial Procedures: An Overview and Defendant's Rights During a Court Trial.)

Alibis and the Burden of Proof

Defendants who offer alibi defenses do not take on the burden of proving to a judge or jury that the alibi is accurate. The burden of proving a defendant guilty beyond a reasonable doubt remains at all times on the prosecution. Of course, a judge or jury can consider the credibility of alibi evidence when deciding whether the prosecution has met its burden.

Following the Ellis Ware scenario, Miriam testifies on behalf of defendant Ellis Ware that he was with her at a Kiwanis Club meeting when the robbery took place. Cross examined by the prosecutor, Miriam admits that she didn't mention this alibi to the police officers who initially interviewed her. During closing argument, the prosecutor tells the jury, "If the alibi were true, Miriam would have said so the first time the police talked to her. She wasn't a believable witness, so you must find the defendant guilty." This argument is improper. Whether or not the jury believes Miriam, the burden remains on the prosecutor to prove beyond a reasonable doubt that Ware robbed the store. Nevertheless, the jury's disbelief of Miriam can add to the persuasiveness of the prosecution's case.

Defendants Must Give Pre-Trial Notice of Alibi Evidence

In most states, if a defendant in a criminal case intends to rely on alibi evidence at trial, laws called "discovery rules" require the defendant to let the prosecutor know beforehand. This gives prosecutors time to investigate the alibi and prepare to undermine it.

For example, let's say Rick Blaine is charged with a sexual assault crime. He plans to offer an alibi defense that he was at the Bijou Theater watching the film Casablanca at the time the assault occurred. Blaine has to notify the prosecution of this planned defense in advance of trial. The prosecution then has time to investigate the alibi. If the investigation turns up evidence that the Bijou theater was showing only Treasure of the Sierra Madre on the date of the sexual assault, the prosecutor might undermine Blaine's alibi by calling the theater's manager as a witness who can testify as to which film was showing on the night in question.

Alibi Evidence: State Law Example

To get a better idea of how laws on alibi evidence work, take a look at this summary of New York's law on the use of alibi evidence in a criminal case:

In the state of New York, prosecutors have up to 20 days following indictment to serve a "Demand for Alibi" on defendants. Defendants who intend to rely on an alibi defense must respond to the demand within eight days, unless the court grants them more time. The response should identify the place or places where the defendant claims to have been at the time of the crime; the name of every alibi witness other than the defendant, and the home address and place of employment of every alibi witness. Defendants must supplement initial responses with information about additional alibi witnesses as they become known. A judge may exclude the alibi testimony of any defense witness whose identity was not disclosed.

Learn More

For everything you've ever wanted to know about the criminal justice system from searches to sentencing get The Criminal Law Handbook by Paul Bergman and Sara Berman (Nolo). And if you need more personal help after an arrest or other run-in with the criminal justice system, use Nolo's trusted Lawyer Directory to find an experienced criminal law attorney near you.