The 9th US Circuit Court of Appeals in San Francisco, USA, has ruled that it is legal to distribute blueprints (i.e. digital plans) for 3D-printed guns online (without approval from the federal government). The ruling overturns a district court order dating back to March 2020, when 22 states and the District of Columbia obtained an injunction that blocked a US State Department rule change aimed to remove 3D-printed guns and associated blueprints from the US Munitions List (which imposes controls on certain types of weapons). However, the Justice Department is planning to issue new rules 'to help stop the proliferation of "ghost guns"', a term used to refer to the fact that 3D-printed guns do not have a serial number, making them difficult to trace.