davefoc
It seems plausible to me right now that the Romans could have assisted some kind of ruling bureaucracy that they supported with a problem.
It is interesting (to me at least) that the Gospels, despite their differences on this point, so realisitcally depict a big-fish-in-a-small-pond bureaucrat covering his behind. Pilate may not understand what Jesus is accused of, or why killing him furnishes any learning experience that a good old-fashioned scourging won't provide just as well, but Pilate does make sure that nobody can come back six months later and say "You killed an innocent nebbish."
Pilate diffuses responsibility, most elaborately in
Luke, where even Herod Antipas signs off on the hoisting. Pilate gets as many other people as possible on the public record, and performs a realistically memorable "This isn't my idea" public ceremony, the infamous hand washing.
It is difficult to understand the Jewish authorities' behavior as depicted in the Gospels. On the other hand, there is a comic realism to arresting somebody without a clear idea of what you're going to do with him. That eventually it would occur to you that the Romans could really hurt the guy rings true, especially if he is indisputably guilty of Roman-law transgressions (it's Gospel), however minor in the larger scheme of Roman law enforcement concerns.
If Jesus' execution was a political favor, the explanatory problem shifts from why the Romans would be interested in a minor transgressor to why the Jewish authorities would expend political capital to rid themselves of Jesus. Jesus doesn't need to be much of a threat or annoyance for somebody to beat him up, though, or for the thought to occur that the Romans are especially skilled at beating people up. Jesus' objective behavior isn't enough to inspire Roman expenditure to snatch him, but if he falls into their hands... maybe he's toast.
Nobodies can easily be ground up in bureaucratic gears. Ask Eddie Slovik (searchable). What killed him? He was more-or-less objectively guilty of a theoretically capital transgression (for which literally nobody else was executed in generations), which opened the door to a process in which responsibility for shooting him was diffused among many decision makers. He was no threat to anybody, nor was shooting him much of an example. But the gears ground, he had ineffective legal help, few political allies, it was war time, and the machinery swallowed him up.
Ethel Rosenberg would be another example. Apparently, the original law enforcement objective was to get her to roll over on her husband, despite the legal protection of married couples. One thing led to another, and they offed her, too. In that case, it was New York State that did a "political favor" for the feds, who were physically unable to carry out a death penalty. To this day, it is unclear whether Ethel really committed any crime, federal or state, at all.