A French judo player (or whatever one does at judo) was disqualified yesterday for touching her opponent's leg. It would be almost comical if it weren't so distressing for the judo-ist involved. Neither 'player' knew what was going on - because neither realised it had happened - and the referee/judge/umpire had to explain.
Apparently, you cannot take your opponent by the leg with your hand (you can use your own leg though) as a first-off move. The French player hadn't attempted a hold, her arm/hand merely touched the opponents leg. Tough call... but them's the rules.