That brings up the interesting question as to whether or not a person is responsible in any country for the consequences of teaching a martial art. That is, if you teach a martial art, and a student uses it, provoked or unprovoked, is the teacher then responsible? Especially if it is used in a manner considered illegal in that country. I doubt that is so, but I couldn't be sure some country or culture would not hold a teach responsible. If that were so, a teacher would need to know the laws of the country for sure. Other than that, a teacher would probably be best advised not to try and become a lawyer as well.
That is an interesting question. I know that according to Uechi-Ryu history, Uechi Kanbun Sensei while teaching in China taught a student who reportedly killed a man over a land dispute. The actual details are fuzzy, and according to some it was actually Uechi Kanbun Sensei that killed a man. But going by the history as presented, Uechi Kanbun Sensei felt such personal responsibility for his students actions that he quite teaching and moved back to Okinawa, vowing to never teach again. This isn't a vow he kept, but it was many years before he actually taught again. A different version of the story is that the Chinese community no longer trusted Uechi Kanbun Sensei and would not allow him to teach any longer.
Closer to home, as a L.E. instructor I am 'somewhat' responsible for what and how I teach. For example, if I teach properly I can be called into court as an expert witness to discuss what was taught, why it was taught and the expected outcome(s). I'm not on trial personally, but I have to be able to intelligently articulate the details of the training and if the Officer/Deputy/Agent used the training according to policy and how it was taught. If I taught something outside the course outline and the Officer/Deputy/Agent used it with a bad outcome I possibly could be called into question. I've not seen that happen, but that isn't to say it couldn't happen or has happened to some instructor somewhere.
Could a martial arts instructor be called into a court of law to explain what he has taught, to whom he has taught it and why he has taught it? Yes. Would he be directly 'on trial'? No. But from a business aspect it probably wouldn't do very well to have bad publicity because you taught something 'incorrectly' or to the wrong person or in an irresponsible manner. I'm not sure there is a criminal law but certainly anyone can be civilly sued.
It would be interesting to hear what other countries do or have done.