WASHINGTON

The Supreme Court is entering the YouTube era.

The first citation in a petition filed with the court last month, for instance, was not to an affidavit or a legal precedent but rather to a YouTube video link. The video shows what is either appalling police brutality or a measured response to an arrested man’s intransigence — you be the judge.

Such evidence vérité has the potential to unsettle the way appellate judges do their work, according to a new study in The Harvard Law Review. If Supreme Court justices can see for themselves what happened in a case, the study suggests, they may be less inclined to defer to the factual findings of jurors and to the conclusions of lower-court judges.

In 2007, for instance, the Supreme Court considered the case of a Georgia man who was paralyzed when his car was rammed by the police in a high-speed chase. The chase was recorded by a camera on the squad car’s dashboard, and that video dominated the court’s analysis.

The federal appeals court in Atlanta had ruled for the driver, Victor Harris, at a preliminary stage in the case, saying a jury should decide whether his driving warranted the aggressive measures taken by the police.