[MikeDubreuil]

I like the yellow and red card idea. It will help teams drive their robots according to the rules.
I don't particularly like the idea of the referees deciding what violates such ambiguous rules as tipping, damage, and agressive. They are great people, but I would rather see some official examples shown to all before the referees rule on a play. The referees are human volunteers (like a lot of us), and only "FIRST officials for a day."