I'd suggest you look up "The Beckwith Incident" (see link below). It sets out how a Florida man repelled a robbery attempt with the use of automatic weaponry. It was an extremely dangerous situation in a rural county at night with a lone citizen against a crew of robbers. The severity of the situation is likely why the use of automatic weaponry and vast number of rounds expended did not lead to a prosecution.
http://www.afn.org/~guns/ayoob.html
I believe "Mete" may be referring to the Gary Fadden incident. The article below provides a good account of the legal ramifications that Fadden faced in the wake of his lawful use of an automatic rifle in self defence.
http://findarticles.com/p/articles/mi_m0BTT/is_168_28/ai_112685749/?tag=content;col1