Scary, isn't it! And how about the student who thinks he is well trained and invincible! Then he gets beat up in a bar brawl and decided to sues his teacher.
We really shouldn't be telling the lawyers all this. . .
On a lighter note, back in 1963, our dojo sent 50 students to Chicago to participate in Count Dante's (and the world's) first world championships! It was a huge event, but as expected,terribly run. Lots of controversy, with certain students from the Count's dojo reappearing in other rings after losing earlier! It was fun though, to be part of what was to become a major part of karate's growth and focus.
Anyway, a couple of my students (Van Canna for one) did very well, in spite of the home course advantage for the "Count's" people. However, one of my brown belts, who lost, walked into my office following the trip, saying he was leaving my dojo and Uechi-ryu. The reason for his departure was that he lost the tournament! If I was the best teacher, how could he have lost the tournament!!!
This person went to Japan and studied another style for a few weeks, returned and opened a dojo teaching that system! Guess what? He made a hard and fast rule that none of his students could compete in tournaments!
Well, at least he didn't sue me!