What does John 18:28 mean?
At this time, Caiaphas was the man currently recognized by the Roman government as Israel's high priest. John skims over the details of Jesus' sham trials with the Sanhedrin (Mark 14:55–65), which is why Jesus was secretly arrested and brought the Caiaphas' home (John 18:12–14). Long before Jesus was taken into custody, these religious leaders had already decided to have Him killed (John 11:49–53). As the high priest, Caiaphas has some authority from Rome to punish criminals and those who violate Jewish law.That authority does not include the death penalty, however, and Jesus' enemies want to ensure He's executed. That means taking Him to the Roman governor, Pilate, and attempting to paint Jesus as a seditionist. They will lean heavily on mob tactics and the threat of civil unrest to coerce him into executing an innocent person (John 19:12–15).
The scribes and Pharisees avoid Pilate's residence due to their interpretation of Old Testament law. Their belief was that close contact with Gentiles, including entering their homes, would make a person ceremonially unclean. Since this is immediately before Passover, they don't want to make that mistake.