Sanhedrin 34 - Who Can Advance Arguments Pro and Con?
In monetary cases anyone can advance arguments in favor of either liability or non-liability. In capital cases, however, anyone may advance arguments for acquittal - even the students who are sitting in court to learn the law - but only the judges may advance arguments for conviction.
In capital cases, one who advanced an argument for conviction may argue for acquittal, but one who advanced an argument for acquittal may not argue for conviction. He needs to keep thinking through his acquittal arguments till the end. In the final vote, however, he may decide for conviction.
Multiple laws may by derived from one verse, but multiple verses may not be used by the same Sage to derive the same law. Therefore, if two Sages in court bring the same argument citing different verses, it counts as only one vote.
Art: Frans Hals - Paulus Berestey, judge at Haarlem