
To curb gun violence, the San Diego City Council in September passed a law to prohibit the sale or possession of unfinished firearm frames, receivers or unserialized firearms — commonly used to build ghost guns.
The effort has gotten attention nationwide and has already attracted legal challenges. But it’s not clear how the city will enforce the law, why state law that already existed was insufficient or just how many people may wake up now having violated the law for having something that wasn’t illegal to own a couple months ago.
It’s also unclear just when exactly a bunch of pieces become an illegal firearm.
The Eliminate Non-Serialized Untraceable Firearms Ordinance, introduced by Councilwoman Marni Von Wilpert, aims to make it harder for people who would not legally be allowed to own guns to manufacture one that evades California’s existing background check system. The New York Times this week covered the role ghost guns have played in violence in U.S. cities, highlighting Von Wilpert and San Diego’s attempt to combat them.
The Firearms Policy Coalition, a pro-gun legal advocacy group, has already filed a suit challenging the city’s ordinance.
Gun violence prevention advocates, meanwhile, argue the local ordinance is closing a loophole in the state law and will make it harder to create an unserialized, working firearm, even if there are still ways to do so. Unserialized is what weapons without traceable serial numbers are called.
Because of the new ordinance, and a lack of a coordinated outreach campaign informing San Diegans that unserialized guns have been banned, local gun owners could now find themselves owning an item that was legal two months ago, and has sat in a safe since then and become illegal without any modification or changes. Because unserialized receivers are not registered, there is no way to notify owners that they are at risk of prosecution for owning an item that was legal at the time of purchase. If owners attempt to contact the California Department of Justice to convert their unfinished receivers into finished firearms (which they can do legally in the rest of the state), they could be admitting to a crime.
San Diego has a history of gun laws used to enhance criminal sentences. In 2019, San Diego introduced a safe firearm storage ordinance. It outlined safe storage practices but it has only been used four times, each as an additional charge in cases where defendants had already broken another law.
Similarly, existing law already allows prosecutors to charge people who manufacture guns illegally. In October, for instance, before the local ghost gun ban went into effect, the San Diego Police Department announced it had seized dozens of firearms, including 28 ghost guns. Officials said three suspects were arrested and charged with a variety of crimes, including unlawfully manufacturing firearms, selling firearms without a license and for violating assault weapons laws.
“The men were arrested on state charges already on the books,” Lt. Adam Sharki, an SDPD spokesman, wrote in an email.
Part of the problem for lawmakers looking to address the issue is that what constitutes these kinds of weapons, commonly known as ghost guns, is open to interpretation, making it difficult to define them in a criminal statute.
The ordinance defines a ghost gun as “a piece of any material that does not constitute the completed frame of a firearm, but that has been shaped or formed in any way for the purpose of becoming the frame of a firearm, and which may be made into a functional frame of a firearm through milling, drilling, or other means.”
Left undefined is exactly when in the shaping process a piece of metal or plastic makes the transition from legal to illegal. Nor does the ordinance make it clear how SDPD will identify ghost gun owners and enforce the new rules, leaving it to the discretion of law enforcement.

Existing Law
Ghost guns fall into two broad categories, each of which is treated differently under state law. What differentiates them from firearms is that the end user must complete the manufacturing process themselves.
The first are “receivers” for long guns, typically AR-type rifles, that can be purchased in person with cash and without a background check in the rest of California and leave no record. They are basically a hunk of metal without the barrel, stock, or trigger and aren’t legally considered complete. These are commonly called “80 percent” receivers, because they are roughly 80 percent complete. An 80 percent receiver becomes legally complete when one uses a drill and a router to make holes for retaining pins and the trigger. Before doing this, a person in California must apply for and engrave a serial number and pass the usual background checks.
The second type of ghost gun relies on a pistol “frame” that is either obtained unfinished or 3D printed. These are virtually impossible to register legally in California. To make it legal, the owner would have to install a piece of metal in the frame (to make it possible to detect with a metal detector) and render it “single shot only” as well as install a very long barrel.
As it stands, one cannot legally make a semi-automatic pistol in California without submitting several models to the California Department of Justice for inspection and without installing “microstamping” technology (which does not yet exist in any retail weapons). Only when these criteria are met can a pistol be included on California’s roster of guns approved safe for sale.
Although loopholes around these rules exist, they are largely reserved for law enforcement. Indeed, the city’s ENUF ordinance does not apply to law enforcement employees on duty. Currently police in California are exempt from the roster requirement and are permitted to purchase guns that have not passed the DOJ safety tests and do not microstamp their bullet casings. Law enforcement officers can also sell their used off-roster weapons to civilians at inflated prices. Between 2013 and 2019, Marco Garmo, a former San Diego sheriff’s captain, illegally sold 98 firearms to citizens, each of which were “off-roster” and thus not considered safe for citizens to purchase in California. He pleaded guilty to selling those weapons without a license to deal firearms.
Von Wilpert issued a general statement defending the ordinance, but would not answer questions about how the city would enforce it, or how 3D printers could circumvent it, or take a stance on the law enforcement loophole. She deferred all questions about implementation of the law to the police department.
Brady United, a national nonprofit that advocates for gun control, supports San Diego’s ordinance, but its press secretary, Liam Sullivan, also noted it doesn’t stop the 3D printing of guns, which has become a growing concern in Europe. The city law would not, for instance, criminalize the possession of digital files used to print a firearm at the press of a button. But it is possible, Sullivan said, that the ordinance allows for the enforcement of physical 3D printed guns because it prohibits the ownership of an unserialized “frame” once it is printed.
“Currently, in California, it is not unlawful to manufacture unserialized firearms, i.e. ghost guns,” said Tanya Schardt, the group’s senior counsel and director of state and federal policy. “However, those who choose to are required to seek a serial number from the California Department of Justice. Currently, all available information suggests that this is not happening, meaning that individuals are purchasing these unfinished frames or receivers and crafting fully functioning firearms that are unserialized and therefore untraceable. This ordinance addresses that loophole; ghost gun parts and kits now cannot be sold, as preventing the sale of these parts will help to address the proliferation of these weapons in the city.”
This argument, however, is somewhat narrow as the ban could be avoided by anyone willing to travel outside of city lines. As Schardt acknowledged, the completion of guns without registering them — at which point they are no longer untraceable — is already a crime under state law. Indeed, the ordinance builds on a series of gun laws that already offer prosecutorial options for anyone building, carrying, selling, or shooting someone with a gun without a serial number. Building a finished weapon without a serial number and possessing that weapon outside of one’s home is already a crime in California, as is removing the serial number from a gun. Selling a gun in California without going through a dealer and background check is already a crime as is manufacturing one without applying for a serial number. It is also illegal for a felon to possess a weapon in California, and in July 2022, Assembly Bill 879 will begin to restrict the transfer and ownership of “firearm precursors” (or unfinished receivers).

the San Diego Police Department’s Ghost Gun Apprehension Team on Oct. 7, 2021. / Photo courtesy of the San Diego Police Department
Enforceability
Despite the prohibitions already in place, ghost gun use does seem to be on the rise. San Diego police report that its officers have seized at least 307 ghost pistols and 48 ghost rifles as of September 2020.
The city’s ordinance, though, specifically excludes weapons made before 1968, before serial numbers were legally required. Firearms can be obtained without a background check if they were made before 1899, making them popular with people who cannot legally own guns. It’s unclear if SDPD’s data on ghost gun seizures includes those types of weapons, which are sometimes used by criminals, because the department has not made the data available to verify.
SDPD has not provided VOSD with information on how many of these types of weapons are used in crimes. They have regularly mentioned that they are recovering more ghost guns than ever before. SDPD’s report to the City Council this summer, before passing the ghost gun ordinance, stated that “the consensus among investigators in the Department’s Special Operations Unit … which focuses on investigating violent crimes, is that 90 percent of the ghost guns recovered by SDPD are manufactured/assembled by a small group of people that sell these firearms through various social media platforms.”
Assembling a weapon like that and selling it on social media is already illegal in California.
Two groups of people who could be prosecuted under the new law, who could not have been before it was passed, are those who own unserialized receivers but have not finished them, or the stores selling them. How SDPD would enforce the law against either group, though, is unclear. SDPD declined to answer questions on how it would do so, citing the ongoing lawsuit. SDPD has not articulated what people who own unserialized receivers purchased prior to the ban should do with them.
John Lemieux, treasurer of the nonprofit San Diego Socialist Rifle Association, said building a ghost gun can be more time consuming than simply purchasing a Glock or AR-15.
“Most of the people buying and building these are just gun enthusiasts who enjoy building things and making their gun exactly the way they want it. “Someone may also not want to have to use an FFL [Federal Firearms License shop] which will generally charge an extra $50 or more to transfer a gun to you after you order it online.”
Lemieux said he remains “very skeptical that this [ordinance] will have any impact on gun violence here in San Diego. The law only applies to the city of San Diego, so if a person who is not able to legally own firearms were so inclined to purchase an 80 percent kit now it would still be pretty easy for them to do so.”
Councilmember Chris Cate, the only member to vote against the ordinance, agreed.
“The vast majority of law-abiding gun owners strictly adhere to federal, state, and local laws regarding purchasing, owning, and transporting firearms, including those laws already in place to address firearms that are homemade,” he said in a statement. “I believe this proposal places an additional undue burden on compliant, responsible gun owners and does nothing to address the real issue of gun violence committed by criminals. Additionally, I see enforcement as the largest challenge for this policy as those same criminals will not self-enforce this new law.”
San Diego County laid the groundwork for a similar ordinance on Oct. 19, with the Board of Supervisors voting to direct staff to draft an ordinance. The two Republicans on the Board voted no. The Board of Supervisors also announced their intent to look into safe storage standards, and prohibitions on 3D printed guns.