In the backdrop of virtually one or two gaffes per game by a ref in terms of penalties, many of which are momentum turning or game breaking, I would propose that each coach have one additional challenge per game, that being for a challenge of a penalty call. At this point, that is not allowed. Yet, the refs continue to mess up and there is no suggestion that competency is on it;s way, so give each coach one penalty challenge per game. For example, Montreal could have used it on the play that resulted in the ref getting canned. Last night, Marcel could have used it on the interference call that changed the momentum of the game. Sure, the refs will bitch as it will clearly put the spotlight on them, but heck, if coaches like Marcel have the spotlight on them for everything, or a player has constant replays, why not a ref just one time per game. Keep this idea in mind as the games unfold and you yourself, see when you would throw the zebra challenge flag. What is wrong with transparency and accountability?
Might have to define the rule as to whether you can challenge it if a flag is thrown and you wish the call to be reviewed with a view to having it waived off, or even go so far as to challenge a play where no flag was thrown so that the challenge results in a flag.