In court proceedings in the United States, a Perry Mason moment is said to have occurred whenever information is unexpectedly (to most present), and often dramatically, introduced into the record that changes the perception of the proceedings greatly and often influences the outcome. Often it takes the form of a witness's answer to a question, but it can sometimes come in the form of new evidence. It takes its name from Perry Mason, a fictional character in novels and stories written by Erle Stanley Gardner, where such dramatic reversals occurred, often in the form of witnesses confessing to crimes others were accused of in response to the sudden exposure of an inconsistency in their alibi.
Because of modern discovery requirements, Perry Mason moments are rare in actual American court proceedings. Both sides are largely aware of what the other plans to introduce as evidence, and judges usually stay or continue proceedings when a party informs the court it has uncovered new evidence, in order that the opposing party be sufficiently prepared. Lawyers, too, prefer not to ask witnesses questions when they do not have a good idea what the response will be. Perry Mason moments that do occur, such as those on live television during the first Menéndez brothers trial and the O. J. Simpson trial, are often the result of careful planning by the lawyers involved. Gambles by lawyers have also resulted in Perry Mason moments, sometimes not for their side, and some have occurred completely spontaneously.
Judicial attitude
The judicial system tries to avoid Perry Mason moments in proceedings in order to keep them fair. In 2001 the federal court for the Northern District of Iowa granted a drug defendant a new trial over prosecutorial misconduct. Among the misdeeds that it cited to support the motion was the testimony elicited from one government cooperating witness who had agreed to take the stand in return for plea agreements or immunity. The witness, visibly nervous, was asked after being sworn in why this was so. She told the prosecutor that another driver had given her the finger and attempted to run her off the road on the way to court that morning; after being asked if she recognized that person, she identified him by name and also as the defendant's sister's boyfriend. The court found that level of detail completely unnecessary, as there were other possible causes of her condition, including a medical diagnosis of anxiety, and it was only when the prosecutor asked that the jury and the defense became aware the driver was connected to the defendant. "Moreover," wrote the district's chief judge, Mark W. Bennett, who had presided over the trial, "this type of a 'Perry Mason' moment, replete with the elements of surprise and prejudice, is precisely the type of matter that should be taken up with the court outside the presence of the jury."
Courts have sometimes cited the unlikelihood of a Perry Mason moment in real life as a justification for their rulings. In 2005, Kent A. Jordan, then sitting on the federal District of Delaware, denied a defense request to grant immunity to a real estate broker the defendant believed had actually been the one to forge a lease rather than the defendants themselves, as the government alleged, so the broker would have no fear of self-incrimination and be compelled to testify. "[I]t is not at all clear that the real estate broker's testimony would be exculpatory", he wrote. "On the contrary, it appears that Leary merely hopes that his counsel will be able to break the broker down on cross-examination. A prayer for a Perry Mason moment does not constitute the kind of 'clearly exculpatory' evidence contemplated in [a precedent].
Five years later the Seventh Circuit heard the appeal of two bank robbers who argued that the trial judge had, by disallowing a line of questioning on cross-examination over one key witness's motivations for testifying, violated their Sixth Amendment right to effective assistance of counsel. The court agreed but held the violation harmless error given the overwhelming evidence against the defendants, who also could not have been certain as to whether the witness would testify as they had hoped. "It is unlikely that counsel expected Simmons to break down on the stand and admit that his perjury was part of an elaborate scheme to frame the defendants", wrote Judge Daniel A. Manion. "Only Perry Mason enjoyed such moments."