Why didn't He defend Himself? Why was He silent?
The Lord became the defender of truth, and came in silence before Pilate, on behalf of truth which had been oppressed (John 18:37-38). Others gain victory through making defenses, but our Lord gained victory through His silence, because the recompense of His death through divine silence was the victory of true teaching. He spoke inorder to teach, but kept silent in the tribunal. He was not silent over that which was exalting us, but He did not stuggle against those who were provoking Him. The worlds of His accusers, like a crown on His head, were a source of redemption. He kept silent so that His silence would make them shout even louder, and so that His crown would be made more beautiful through all his clamor.
Why was our Lord wearing white?
It is significant that Jesus is clothed in a white garment by Herod. It denotes His sinless passion; because the Lamb of God without stain and with glory accepted the sins of the world. (John 1:29) Herod and Pilate, who became friends instead of enemies through Jesus Christ, symbolize the peoples of Israel and the Gentiles, since the future harmony of both follows from the Lord's passion (Eph 2:13) First, the people of the nations capture the Word of God and bring it to the people of the Jew, through the devotion of their faith. They clothe with glory the body of Christ, who they had previously despised.
Note: Now our Lord is wearing the white garments, but in the next hour, they shall be crimson, reddened by our sins and stained by our iniquities.