What does John 18:22 mean?
What modern people think of as "civil rights" did not meaningfully exist in most ancient cultures. However, the basic concepts of law and order usually applied. Beating a person suspected of committing a crime has been frowned upon by most law-minded societies. While the man striking Jesus is not necessarily trying to beat a confession out of Him, his actions are not part of protocol. Either under Jewish tradition (Deuteronomy 25:1–2; John 7:51), or Roman law, what's happening here was probably illegal.The real motivation for this assault is the pointed comment Jesus has just made. In essence, He called out the high priest for hypocrisy. He challenged His accusers to provide evidence for their allegations (John 18:20–21). Few things inspire as much rage as having one's wrongdoing exposed (John 3:19–20). Authority figures have a habit of mistaking defense for defiance, punishing underlings simply because they don't bow and scrape with enough reverence. Likewise, criticizing someone's tone is a common way to avoid responding to the substance of their argument.
Jesus will respond by emphasizing this last idea: if His words are false, His accusers should prove it, and if they are true, there is no cause for them to react with violence.