"When men take it in their heads to day, to hang gamblers, to hang murderers, they should recollect, that, in the confusion usually attending such transactions, they will be as likely to hang or burn some one, who is neither a gambler nor a murderer as one who is; and that, acting upon the example they set, the mob of to-morrow, may, and probably will, hang or burn some of them by the very same mistake. And not only so; the innocent, those who have ever set their faces against violations of law in every shape, alike with the guilty, fall victims to the ravages of mob law; and thus it goes on, step by step, till all the walls erected for the defence of the persons and property of individuals, are trodden down, and disregarded. But all this even, is not the full extent of the evil. By such examples, by instances of the perpetrators of such acts going unpunished, the lawless in spirit, are encouraged to become lawless in practice; and having been used to no restraint, but dread of punishment, they thus become, absolutely unrestrained." - Abraham Lincoln, "The Political Religion of the Nation" (Jan. 27, 1838)
Although Lincoln was speaking to citizen organized vigilante justice, I find the point equally applicable to government organized vigilante justice.