Where does it say...

Anti-gunners keep tossing around the tired old claims when referring to what they like to call "assault weapons". They claim "these weapons were meant for killing lots of people very quickly", "these are the weapons that criminals prefer to use", "these weapons have no sporting value", "nobody has any legitimate reason to have one of these", "nobody needs these guns", etc.

I'm sick and tired of hearing it. Show me what legislation states that a gun has to possess "sporting value" to be considered legal.