The thread on trial breaks reminds me of the first trial I attended here, where a very Texan trial lawyer stood up and Michael Scott declaring bankruptcy style bellowed "Judge I invoke the Rule" and everyone acted like they knew what it was, and I was very puzzled. 1/

As is now obvious, what he meant was the Rule excluding all witnesses other than the one testifying from the courtroom. And Texas lawyers always call it "The Rule" without any elaboration. But I was totally baffled.

The idea is that you don't want the other witnesses sitting there listening to the story this one is telling.

It doesn't apply to expert witnesses, who basically should know what everyone else thinks.