The implied rule that since we were testing out skills against each other there would be no interference. That we would be nice enough to follow society's rules by not killing each other. That we would call 911 or drive the other to the hospital if either person required immediate medical attention. I ended one by knockout and one by verbal tap out due to strikes. I was actually the one who was playing nice. Actually it's funny that they're effective NOW but when they were allowed they weren't all that effective and that was in tournament style events where people had to fight another few opponents afterward.