We've seen that the Cons have some Gladiator-games going now and then for prisoners and such, like when those 3 cons had taken over Cybertron in Megs absence.
And then there's Straxus, who does appear to have it down, melting down Autobots and neutrals (mayhaps a con or two?) in the smelting pool. Ouch..
Megs/Galvatron himself doesn't appear to be that keen on laws tho, now is he? A background as a gladiator-punk, with more tattoos in his paint-job than a jigsaw-puzzle, and a great feeling that the government is rotten and useless.
It's mostly "do as I say or I'll slag ya! And we're gonna make some good stuff! Do dat' an' I dun' care bollocks all what you do in your own time".
Can pretty much sum it up, yes? With all the illegal dealings of lads like Swindle and the like.
And then we come to the perhaps defining moment of "Decepticon-Justice". The crufixion of Rodimus Prime on the WTC-towers in Rhythms of Darkness.

Crime? I suppose it was being an Autobot and trying to stand in the way of Galve's.
Do you lads perhaps have any other shining nuggets of examples of Decepticon Justice, and thought on the way it's enforced among the Cons themselves?