When does jeopardy attach at a jury trial?

Jeopardy attaches in a jury trial when the jury is sworn in. This is a crucial point in the legal process, as it marks the formal commencement of the trial proceedings, where the defendant is now under the legal protection of the court against double jeopardy. Once the jury is sworn, the defendant cannot be tried for the same offense again if acquitted, or even if the trial results in a mistrial without a valid reason.

This principle serves to protect the rights of defendants and emphasizes the importance of the jury's role in determining the outcome of the case. It's during this period that the state assumes the burden to prove its case, and the defendant is at risk of being found guilty.

Other points such as when the first witness is sworn in, when jurors are selected, or when the judge begins the trial do not establish the formal risk of conviction for the defendant, which is the defining moment for jeopardy in a trial context.