The short story is:

A Florida inventor who created a device to increase the rate of semiautomatic rifle fire has asked the U.S. Supreme Court to hear his lawsuit against the Bureau of Alcohol Tobacco, Firearms and Explosives, which ruled the apparatus constituted an illegal machine gun.

William Akins, of Hudson, near Tampa, says the ATF at first approved his Akins Accelerator, then reneged after he went into production. A federal judge ruled for the ATF; the 11th U.S. Circuit Court of Appeals upheld that ruling Feb. 4.

A great starting point for the background story is here.

My expectation is the SC will decline to hear the case.