Honestly, outside of the movies, people do not go to martial arts studios to gain skills for the use of commiting crimes.
Joab: citation needed
I think you would find the percentage of serial rapists, muggers, and robbers who learned a deadly martial art and then used it to commit crimes or engage in a nebulous 'illegal activity' to be very, very low.
Joab: I would like a statistical read out for this little piece of pontification on your part. Sorry Daniel, your going to have to do better than just state arbitrarily as facts things that you have no evidence for at all for me to buy it.
The MA of choice for most criminals is gun-fu, not gung fu.
Daniel
Joab: Daniel, not all systems merely teach hand to hand combat. The system I am referring to teaches modern weapons, and the teacher has written a gun column for years and books on point shooting. He is an expert with the knife, stick you name it really. Granted, he no longer teaches point shooting, and granted, he doesn't teach the really nasty techniques to everyone and the modern weapons to everyone, which is the point, he is selective. And there have been the small number of flakes and misfits who tried to enter his school and were either not allowed to enter or kicked out after entering. The hand to hand is rather brutal, nasty stuff that has been taught to British Commandoes and the OSS in World War II.
That said, you are likely right that typically the nut case and criminal will just go out and buy a gun, but it only takes one to cause a lot of damage. And in this age of terrorism, there is the real danger of training the wrong person.