What does Luke 23:4 mean?

The "whole company" of elders, chief priests, and scribes has brought Jesus to Pilate (Luke 22:66; 23:1). The chief priests and elders have turned a crowd against Jesus, as well (Matthew 27:20). As a group, they want Pilate to convict Jesus of a capital offenses and crucify Him. Yet not all individuals in the group agree (Luke 23:50–51). They introduce Jesus as "this man" (Luke 23:2) a derogatory, dismissive term. Pilate repeats their phrase as if to say Jesus is harmless.

This is the first of four times in the chapter where Pilate shows he believes Jesus is innocent, and the first of three times he states it plainly. Pilate will repeat his findings after Jesus returns to Herod (Luke 23:13–14). When the crowd responds with calls that Pilate should take Jesus and release Barabbas, Pilate tries to release Jesus (Luke 23:20). They shout to crucify Jesus, and Pilate again asks what Jesus has done (Luke 23:22).

Here, when the chief priests press, Pilate sends Jesus to Herod Antipas. Ironically, Antipas has referred to himself as "King Herod" for years (Mark 6:14). Josephus, in The Wars of the Jews 2.181, explains that when Antipas finally asks emperor Caligula to be granted the title "king," Agrippa brings to light Antipas has enough weapons for 70,000 soldiers. Instead of giving Antipas more power, Caligula sends him into exile in Spain.

Pilate knows that Jesus claiming to be king doesn't mean He's a threat. He's a poor itinerant teacher. If He had a history of trying to grasp for power and suddenly showed up with several thousand soldiers—or even armed laborers—then He would be a threat. Later, Pilate will attack a group of Samaritans on Mount Gerizim. Contrary to what He seems to think, they are not armed; they are farmers caught under the influence of a false prophet who claims to know the location of artifacts left by Moses. Pilate's vicious response leads to his removal. This is recorded in Josephus' Antiquities of the Jews 18.4.1–2.

We don't know who the "crowd" is. Jerusalem is filled with tens- or hundreds of thousands of people. It's unlikely this crowd is the same that accompanied Jesus during the triumphal entry (Luke 19:28–40). In a few years, Jews in Jerusalem from Cyrene, Alexandria, Cilicia, and southwest modern-day Asia Minor will kill Stephen. A couple of decades later, Paul will be attacked by people from the province of Asia (Acts 6:9; 21:27). The crowd that demands Jesus' death may be made of Jews who have traveled for the Passover from the Roman Empire who don't know anything about Jesus. It would be disconcerting to finally return to Jerusalem to worship at the temple and discover—they think—a false prophet is claiming to be the Christ.