Gemara Shevuos 31a says that if two people come to Bais Din one dressed in rags and the other dressed in expensive clothing, we make them dress similarly. Sefer Hachinuch Mitzva 235 indicates that ...
There is an interesting t'shuva in Igros Moshe Choshen Mishpat vol.2 #68 (pt. 1 pt. 2) in which he explains the extreme rarity of capital punishment in Jewish law, especially in modern times. It is ...