I would guess that each State and unit of local government would have their own and probably not very uniform rules to issue permits for keeping venomous snakes. The reason that somebody would be issued permits to keep them is because somebody must have possession of hots to obtain venom from to make antidotes to snake bites and for man to have knowledge of venomous snakes. Most people with permits probably have science related degrees and can claim to be doing some sort of research or study. Although the law of averages would allow for some places to issue permits to anybody that applies for one.