To me, they're way past the time when normal legal means would have solved this issue. Their parliament should take a vote and pass a law allowing for it. That way it's legal. There should be an impartial review board, and they should assure that this doesn't become a tool for unsanctioned revenge killings. I'm talking about martial law.
They've had martial law in pockets. No sense doing it for the entire country since most of the country is doing alright. The bottom line is this: Three distinct factions are going to have a tough time making hard or quick decisions. They've been in power for about a year? They have no sea legs. That is why we need to be there. The war is over. Now its about stomping out criminal, sectarian enterprises. Its best that the Iraqis do as much of that heavy lifting as possible. And in many cases they are. Look at SandRats daily posts to see that not everything is going to hell in a handbasket there.