There is a Supreme Court ruling that already directly relates to the current Assault Weapon Ban.
In United States v. Miller 1939, Miller possessed a sawed-off shotgun banned under the National Firearms Act. He argued that he had a right to bear the weapon under the Second Amendment. The Supreme Court ruled against him. At the time, sawed-off shotguns were not being used in a U.S. military application. The Miller case set the precedent that protected firearms have a military and thus a legitimate and protected Militia use.
The AR-15/AK-47 type weapon is currently in use by the American military. Therefore, it is a protected weapon for the Unorganized Militia, which includes just about every American citizen.