And I'm sorry, but I don't believe this goody-good argument that all of Kabuto's threats and testiments to rigging the trial (fresh after murdering someone) don't mean anything at all. Come on now. I'm reading posts that would say to let him have a trial, KNOWING that he will get away with it (and make Hinjo lose face in the process), and that anything else would be evil. What you're saying is that there's no way to capture or incriminate this villain. If a DM wrote that scenario into my D&D game, I might be looking for a new group.
While V's methods were crude, the results in my opinion have more likely spared many more deaths and injustices (and I say V is just as qualified as anyone to judge; after all, what places a judge above other mortals?).