Isa 53:7 He was oppressed, and he was afflicted, yet he opened not his mouth: he is brought as a lamb to the slaughter, and as a sheep before her shearers is dumb, so he openeth not his mouth.
I've often thought how good it was that Jesus remained silent before his accusers. Think about how his words silenced the religious leaders when they tried to trick him with their questions (about paying taxes, about the 7 men who had each been to the same woman, etc). I have no doubt that His words would have silenced his critics once again, and given Pilate little less to work with moving the 'trial' ahead.