18:28-19:16: John’s account of the hearing before Pilate is unique, among the gospel accounts, in the following ways:

• mention of the Jewish leader’s avoidance of ritual impurity, and
• their denial that they have the right to execute Jesus. [ CAB]

18:28: “early in the morning”: Dawn would have been a common time for the Roman governor to conduct a hearing; however, the condemnation of Jesus several hours later (“about noon”, 19:14) seems out of order. Some scholars suggest a symbolic reference to the Passover lambs. [ NJBC]
18:28: “ritual defilement”: Entering a Gentile’s house would make them ritually unclean. [NOAB] However, NJBC says that merely entering the praetorium in a legal setting would not have made them unclean. BlkJn agrees with NOAB.
18:28: “the Passover”: It began that evening – at the start of the next Jewish day. [ BlkJn]
18:29-31: The Jews tried religious cases, but could not administer the death penalty. [ NOAB]
18:29: “Pilate went out ...”: A Roman governor could conduct a trial according to his own rules, but a more formal charge than Jesus’ accusers give would be required. [ NJBC] However, Pilate’s words are the correct formal opening of a Roman trial. [ BlkJn]
18:30: Jesus’ death is to be brought about through the Romans, but on the basis of a prior understanding with Pilate rather than as the result of a direct accusation now. It is only when this attempt fails that accusations are laid. [ BlkJn]
18:31: “Take him yourselves ...”: Pilate tries to get out of his understanding with the Jews. Perhaps a subsidiary motive of the Jews was to discredit him as Messiah in view of Deuteronomy 21:23: “ anyone hung on a tree is under God's curse”. Jesus was so popular that they needed Pilate’s help if they were to dispose of Jesus. Jesus is discredited with his supporters (because he is not the sort of king they want) and is also misrepresented before Pilate, who becomes profoundly suspicious of the Jews’ motives and decides to interrogate Jesus away from his accusers. [ BlkJn]
18:32: “the kind of death he was to die”: i.e. crucifixion, rather than the Jewish method of stoning. John reminds his readers that Jesus has predicted how he would die: see 3:14 (“And just as Moses lifted up the serpent in the wilderness, so must the Son of Man be lifted up”) and 12:32 (“And I, when I am lifted up from the earth ...”). [NOAB] Jews were permitted to execute Gentiles who violated the temple precincts. Some Roman historians think it unlikely that they would be permitted to carry out any other capital sentences, especially in Judea. Irony is at play here: in 8:34-37 Jesus has already charged “the Jews” with acting against their own law in seeking to kill him, and in 7:51 Nicodemus accuses them of condemning Jesus illegally, but now they show sudden concern for “your law” (v. 31). [ NJBC]
18:33: “Pilate”: Pilate was prefect of Judea from 26 to 36 AD.
18:33: “Are you the King of the Jews?”: Pilate cannot believe this claim could be made by, on behalf of, the man before him. (He has presumably been told of Jesus’ messianic claims before his arrest.)
18:35: Pilate’s suspicion of the high priests is already apparent. [ BlkJn]
18:36: Jesus puts into words the dilemma he has been in throughout his ministry: though conscious of an absolute authority, and of Davidic descent, he has known that to assert his authority by force would ruin the purpose for which he has come. [ BlkJn]
18:37: “‘You say that I am a king’”: Pilate and Jesus mean different things by kingship, so a direct answer is not possible. [ BlkJn]
18:37: “the truth”: For Jesus’ testimony to “the truth”, see 5:32; 8:40, 45, 46. 8:44 tells us that the Jews have rejected “the truth”. The disciples have received it from Jesus: see 14:6; 17:17, 19. [NJBC] Here, it means reality. [ BlkJn]
18:37: “listens to my voice”: See also 10:3, 4, 16, 27 (Jesus the shepherd who gives his life). [BlkJn]