606 Competency of juror as witness

Here's a plain English summary of this rule:

If you're serving on a jury for a trial, you can't also be a witness in that same trial. You can't sit on the jury and then take the stand to give testimony in the case you're deciding. These are two separate roles, and the law keeps them apart.

The lawyers don't even need to object if this comes up. Normally, if a lawyer doesn't object to something during a trial, they lose the right to complain about it later. But this rule is different. Because mixing these roles is such a basic problem, the court can address it even without anyone raising a formal objection at the time.

This rule protects the fairness of the trial. A juror is supposed to listen to evidence and stay neutral until it's time to decide the case. If that same person also testified as a witness, it would blur the line between judging the facts and being part of the facts. Keeping these roles separate helps make sure the jury's decision is based on a fair and clear process.