Why was Jesus taken to the Sanhedrin after his arrest?

The answer is in the synoptic gospels, Jesus was taken to the Jewish religious court, the Sanhedrin, so that it could determine the charges against Jesus to be brought to the Roman governor, Pontius Pilate.

The author of John's Gospel was aware that the Sanhedrin would never have sat at night to try Jesus, so changed this. In John, Jesus was brought to the home of Annas, father-in-law to Caiaphas, the high priest John 18:13). Annas interrogated Jesus and then sent him to the house of Caiaphas (John 18:24), who in turn sent him for trial under Pontius Pilate..