It has been unlawful since 1934 (The National Firearms Act) for civilians to own machine guns without special permission from the U.S. Treasury Department. Machine guns are subject to a $200 tax every time their ownership changes from one federally registered owner to another, and each new weapon is subject to a manufacturing tax when it is made, and it must be registered with the Bureau of Alcohol Tobacco and Firearms (BATF) in its National Firearms Registry.
To become a registered owner, a complete FBI background investigation is conducted, checking for any criminal history or tendencies toward violence, and an application must be submitted to the BATF including two sets of fingerprints, a recent photo, a sworn affidavit that transfer of the NFA firearm is of "reasonable necessity," and that sale to and possession of the weapon by the applicant "would be consistent with public safety." The application form also requires the signature of a chief law enforcement officer with jurisdiction in the applicant's residence.
Since the Firearms Owners' Protection Act of May 19, 1986, ownership of newly manufactured machine guns has been prohibited to civilians. Machine guns which were manufactured prior to the Act's passage are regulated under the National Firearms Act, but those manufactured after the ban cannot ordinarily be sold to or owned by civilians.
Since 1934, there appear to have been at least two homicides committed with legally owned automatic weapons. One was a murder committed by a law enforcement officer (as opposed to a civilian). On September 15th, 1988, a 13-year veteran of the Dayton, Ohio police department, Patrolman Roger Waller, then 32, used his fully automatic MAC-11 .380 caliber submachine gun to kill a police informant, 52-year-old Lawrence Hileman. Patrolman Waller pleaded guilty in 1990, and he and an accomplice were sentenced to 18 years in prison. The 1986 'ban' on sales of new machine guns does not apply to purchases by law enforcement or government agencies.
Two homocides in 71 years....we need to take drastic action.