In fulfillment of the description of the suffering servant in Isaiah 53, Jesus does not open his mouth. If the totality of his ministry wasn't enough to silence his critics, then a verbal defense won't help. Jesus has the power to stop these events, but his silence in defending himself is just one more way he shows he is going to follow through with the will of God no matter the personal cost to himself. A priestly system that had grown corrupt and sold out to the Roman political machine could and would not judge him fairly. Their only desire was to stay in power. Jesus will not dignify them with a self-defense. He needs none to prove his innocence and he has already chosen to suffer the humiliation of what he will face to honor God and to save us.