The Gospel according to Luke, chapter 23, verse 9, reads as follows:
So Herod questioned him at considerable length; Jesus gave him no answer. (NET)
Then he questioned with him in many words; but he answered him nothing. (KJV)
Why did Jesus not respond to Herod? What reason was there for him not to do so?
He was oppressed and He was afflicted, Yet He opened not His mouth; He was led as a lamb to the slaughter, And as a sheep before its shearers is silent, So He opened not His mouth.
(Isaiah 53:7 NKJV)
Since Jesus did speak before the High Priest and before Pilate, His not speaking before Herod is the means by which Isaiah 53:7 was fulfilled.
Each of the trials was before a different authority:
Herod was "king" over a limited territory of Israel and over a limited number of Jewish people. Jesus was ultimately executed for this reason:
Now Pilate wrote a title and put it on the cross. And the writing was: JESUS OF NAZARETH, THE KING OF THE JEWS. (John 19:19 NKJV)
This declaration by Pilate recognized Jesus as King of the Jews, a legal title which would include those Jewish people scattered throughout the Roman Empire. This contrasts with Herod whose kingship was over a limited part of Israel (Galilee and Paraea). So as a sheep is silent before its shearers, Jesus was silent before Herod who "shearing" Him of a limited kingdom (Herod's). But Jesus is not silent before the High Priest who cannot take away His position as the True and Great High Priest and He is not silent before Pilate who will recognize Him as King of all Jewish people.
Mark records that the Herodians 1 were complicit in a plot to destroy Jesus:
And the Pharisees went forth, and straightway took counsel with the Herodians against him, how they might destroy him.
-- Mark 3:6 (KJV)
It is recorded both in Matthew and Mark that the Herodians 1 were sent to try to entangle/catch Jesus in his talk/words:
15Then went the Pharisees, and took counsel how they might entangle him in his talk. 16And they sent out unto him their disciples with the Herodians, saying, Master, we know that thou art true, and teachest the way of God in truth, neither carest thou for any man: for thou regardest not the person of men.
-- Matthew 22:15-16 (KJV)And they send unto him certain of the Pharisees and of the Herodians, to catch him in his words.
-- Mark 12:13 (KJV)
Mark records, also, that Herod was somewhat of a lunatic, admitting to having killed John the Baptist on a whim, and imagining Jesus to be John reincarnated,:
14And king Herod heard of him; (for his name was spread abroad:) and he said, That John the Baptist was risen from the dead, and therefore mighty works do shew forth themselves in him.
15Others said, That it is Elias. And others said, That it is a prophet, or as one of the prophets. 16 But when Herod heard thereof, he said, It is John, whom I beheaded: he is risen from the dead.
-- Mark 6:14-16 (KJV)
Mark records Jesus as saying of Herod:
... Take heed, beware of the leaven of the Pharisees, and of the leaven of Herod.
-- Mark 8:15 (KJV)
Herod felt threatened by Jesus, which is the clear implication of the introductory words to the question put to Jesus by the Herodians, "Master, we know that thou art true, and teachest the way of God in truth, neither carest thou for any man: for thou regardest not the person of men."
So, when he was taken to Herod, Jesus had absolutely no illusions that his talk/words would have any impact on the outcome of the meeting.
Herodians:
Priestly party under the reign of King Herod and his successors; called by the Rabbis "Boethusians," as adherents of the family of Boethus, whose daughter Mariamne was one of the wives of King Herod, and whose sons were successively made high priests by him.
-- Jewish Encyclopedia
I wonder if Jesus' silence was due to Herod Antipas cutting off the head of His messenger, John the Baptist. One might say, cut off the head of a prophet and cut off the voice of God...
Truly Jesus' silence is a fulfillment of Isaiah 53:7. However, we may wonder that Jesus was not completely silent as He did response to the trial before the Sanhedrin and Pontius Pilate.
Isaiah 53:7 states, "he was led like a lamb to the slaughter, and as a sheep before its shearers is silent". This statement implies that Jesus' crucifixion was His destiny, as if a sheep before its shearers. In Luke 24:44, Jesus revealed this truth to His disciples said, "This is what I told you while I was still with you: Everything must be fulfilled that is written about me in the Law of Moses, the Prophets and the Psalms". Therefore the author of Hebrews wrote in Hebrews 10:5, 'Therefore, when Christ came into the world, he said: “Sacrifice and offering you did not desire, but a body you prepared for me"'
It is important to note the questions that Jesus responded to;
In Luke 22:70, the Sanhedrin members asked Jesus, "Are you then the Son of God?". A similar question is found in Matthew 26:63 and Mark 14:62.
In Luke 23:3, Pontius Pilate asked Jesus, "Are you the king of the Jews?". A similar question is found in Matthew 27:11; Mark 15:2 and John 18:33
In both questions, Jesus either answered "I am" or "You have said so". The significance of this answer is, Jesus did not cover His identity even when facing His destiny. This sets an example for all Christians. Though they are set apart from the world, they should not give up their identity, even when their lives are threatened.
As for Why Jesus did not respond to Herod?. It was because Herod only hoped to see Jesus perform some miracles (Luke 23:8), something for curiosity or pleasure. Jesus did not entertain such expectations, just as He did not give miracles to the crowd and the Pharisee (Luke 11:29; Matthew 16:4).
Several answers have provided plausible reasons but one has not been mentioned yet: namely, Herod Antipas had no jurisdiction in the case. It had been brought by the high priest in Jerusalem and referred to Pilate, the governor of Judea under Roman law. Antipas was the ruler of Galilee. This was probably not the only factor in Jesus' preferring Pilate's court to Herod's but it does help explain why Jesus would refuse to answer. This court was not the proper venue for the trial.
Other factors would include:
Jesus had potential allies in Pilate's court such as Nicodemus, Josephus of Arimathea and Pilate's wife.
As other answers mentioned, Herod was a known enemy while Pilate seemed open to letting Jesus go.
Conversely if we presume that Jesus wanted to die on the Cross in Jerusalem, he would have wanted to avoid being sentenced by Herod. Under the latter's authority (as a Jewish ruler) Jesus would not have been crucified but possibly beheaded; and the punishment would have been carried out in Herod's jurisdiction, not in Jerusalem.
It is only in Luke's Gospel that we find Pontius Pilate asking Herod Antipas to try Jesus, as the other New Testament gospels tell us that Pontius Pilate alone tried Jesus, with no apparent possibility of those gospels merely omitting involvement by Herod: Matthew 27:11-26; Mark 15:1-15; John 18:29-19:16.
Luke chapter 23 does not tell us why Jesus did not respond to Herod, but an interpretive approach can do so. Luke 23:8 tells us that Herod Antpas was exceeding glad to see Jesus:
Luke 23:8: And when Herod saw Jesus, he was exceeding glad: for he was desirous to see him of a long season, because he had heard many things of him; and he hoped to have seen some miracle done by him.
This is anomalous, given that elsewhere, Herod is portrayed as fearful of Jesus (Mark6:16) or threatening towards him (Luke 13:31):
Mark6:16: But when Herod heard thereof, he said, It is John, whom I beheaded: he is risen from the dead
Luke 13:31: The same day there came certain of the Pharisees, saying unto him, Get thee out, and depart hence: for Herod will kill thee.
The clear majority of New Testament scholars say that Luke was substantially copied from Mark, with additional sayings material taken from the hypothetical 'Q' document (John Dominic Crossan says in The Birth of Christianity, pages 110-111, that the consensus for Markan priority is "massive"). The significance of this is that the author of Luke's Gospel is unlikely to have known anything about the trial and crucifixion of Jesus other than what he learnt from Mark's Gospel. The involvement of Herod Antipas was therefore an elaboration introduced by Luke's author, which explains why the other evangelists knew nothing of this, and why Herod is portrayed as uncharacteristically glad to see Jesus.
Herod did not question Jesus at his trial, but portraying Jesus as not answering him is consistent with what we are told in Mark's Gospel, when Jesus refused to answer his accusers:
Mark 15:2-5: And Pilate asked him, Art thou the King of the Jews? And he answering said unto him, Thou sayest it. And the chief priests accused him of many things: but he answered nothing. And Pilate asked him again, saying, Answerest thou nothing? behold how many things they witness against thee. But Jesus yet answered nothing; so that Pilate marvelled.
In summary, the author of Luke's Gospel elaborated the Markan account of the trial of Jesus, by adding the story of Pontius Pilate asking Herod to try Jesus. He portrayed Jesus as responding to Herod in the same way Jesus had responded to Pontius Pilate and to the chief priests in the original account, Mark 15:2-5.
