605 Competency of judge as witness

The judge running a trial cannot also be a witness in that same trial. A judge's job is to oversee the case and make rulings, not to give testimony about what happened. This keeps the judge neutral and avoids a confusing situation where the same person is both deciding the case and providing evidence for it.

If a judge tries to testify, the lawyers don't need to speak up and object to protect their client's rights on this issue. The problem is automatically preserved for appeal, meaning it can be raised later even if nobody objected at the time. This makes sense because judges have a lot of authority in the courtroom, so it would be awkward for a lawyer to challenge the judge directly during the trial.