and solve the crimes. In 2017 alone, the Bureau of Alcohol, Tobacco, Firearms, and Explosives conducted 408,000 traces. (7) Firearms tracing depends on the ability to identify firearms based on their serial number. Traditionally, when a firearm is manufactured domestically or imported from abroad, it is engraved with a serial number and markings that identify the manufacturer or importer, make, model, and caliber, and are unique to the firearm. Firearms made by unlicensed individuals with 3D printers, however, do not contain genuine serial numbers. (8) Criminals seek firearms without serial numbers because they cannot be traced. In July 2018, the Los Angeles Police Department completed a 6-month-long investigation that resulted in the seizure of 45 firearms, some of which had been assembled without serial numbers in order to be untraceable. If the schematics for 3D printing firearms and firearm parts are available online, people intending to commit gun crimes may create similarly untraceable firearms in order to avoid accountability for these crimes. (9) Interstate gun trafficking, including the trafficking of untraceable firearms, interferes with lawful commerce in firearms and significantly contributes to gun crime. Of the 211,384 firearms traced by the Bureau of Alcohol, Tobacco, Firearms, and Explosives in 2016, 60,936 of those firearms were originally sold by a licensed firearms dealer in a State other than the State where they were recovered. These guns made up 28.8 percent of all firearm recoveries in 2016. (10) The proliferation of 3D-printed firearms threatens to undermine the entire Federal firearms regulatory scheme and to endanger public safety and national security. By making illegal the publication of certain computer code that can be used automatically to program 3D printers and create firearms—the only means of combating this unique threat—Congress seeks not to regulate the rights of computer programmers under the First Amendment to the Constitution of the United States, but rather to curb the