Now it was the third hour, and they crucified him, and the superscription of his charge was superscribed: “The king of the Judaeans.” (Mark 15:25-26)
And over his head they put the charge against him written: “This is Jesus, the king of the Judaeans.” (Matthew 27:37)
Now there was also a superscription over him, “This is the king of the Judaeans.” (Luke 23:38)
Now Pilate also wrote a title and put it on the cross, and it was written, “Jesus the Nazorean, the king of the Judaeans.” Then many of the Judaeans read this title, because the place where Jesus was crucified was near the city, and it was written in Hebrew, in Roman, in Greek. So the chief priests of the Judaeans said to Pilate, “Do not write, ‘The king of the Judaeans,’ but that, ‘This man said, I am king of the Judaeans.’” Pilate answered, “What I have written I have written.” (John 19:19-23)
A resume of the crime(s) that a person had perpetrated, written on a sort of tablet, was sometimes either hung around the neck of a condemned person or paraded on a sign before him as he was marched or dragged to the site of execution.
And inasmuch as some of the jurymen voted to acquit even these conspirators, the emperor [Augustus] made a law that in trials at which the defendant was not present the vote should not be taken secretly and the defendant should be convicted only by a unanimous vote. Now that he took these measures, not in anger, but as really conducive to the public good, he gave very strong proof; at any rate, when [Fannius] Caepio’s father freed one of the two slaves who had accompanied his son in his flight because this slave had wished to defend his young master when he met with death, but in the case of the second slave, who had deserted his son,
led him through the midst of the Forum with an inscription making known the reason why he was to be put to death, and afterwards crucified him, the emperor was not vexed.
At a public banquet in Rome [Caligula] immediately handed a slave over to the executioners for stealing a strip of silver from the couches, with orders that his hands be cut off and hung from his neck upon his breast, and that he then be led about among the guests,
preceded by a placard giving the reason for his punishment.
A householder who said that a Thracian gladiator was a match for the murmillo, but not for the giver of the games, [Domitian] caused to be dragged from his seat and thrown into the arena to dogs,
with this placard: "A favourer of the Thracians who spoke impiously."
- Suetonius, Caligula 32; Domitian 10
But Attalus was called for loudly by the people, because he was a person of distinction. He entered the contest readily on account of a good conscience and his genuine practice in Christian discipline, and as he had always been a witness for the truth among us.
He was led around the amphitheater, a tablet being carried before him on which was written in the Roman language ‘This is Attalus the Christian,’ and the people were filled with indignation against him. But when the governor learned that he was a Roman, he commanded him to be taken back with the rest of those who were in prison concerning whom he had written to Caesar, and whose answer he was awaiting.
- Eusebius, Church History 5.1.43-44
In all the above passages, only one directly deals with a crucifixion. So it would seem that this was an occasional practice of variable application. Also, all of the above passages only speak of the placard in the context of the parading of the victim; the posting of the accusation on the cross is not-well attested, either because those describing crucifixion had already mentioned its being carried or because the practice was not standard. In fact, some think that the reason why this detail was remembered is precisely because it was unique.
‘King of the Judaeans’ (or traditionally, ‘king of the Jews’) is not a religious term, but a political one (cf. Josephus,
Antiquities 14.36; 15.373; 16.311, all in reference to Herod the Great;
Jewish War 6.104, of the Judahite king Jeconiah/Coniah/Jehoiachin; 7.171, “Alexander [Jannaeus], the king of the Jews;” Plutarch,
Pompey 45.5 “Aristobulus, king of the Jews”). While there were a few people who doubted the historicity of the inscription, the early Christians generally hesitated to explicitly grant the title ‘king’ for Jesus for political reasons, so the title is not confessional and thus, is unlikely to have been fabricated. The title is not so much a formal statement of charges as it was an expression of Roman ridicule for a supposed insurrectionist who was made out to be king.