California ghost-gun bill wants 3D printers to play cop, EFF says
Proposed law could lock down open source tools and give vendors fresh reasons to inspect print files
California's proposed legislation to put the burden of blocking 3D-printed firearms onto printer manufacturers could effectively sideline open source tools and create new surveillance concerns, digital rights activists argue.
Advocates at the Electronic Frontier Foundation (EFF) say that such legislation could empower manufacturers to introduce restrictive policies affecting consumer choice. It could lead to widespread surveillance of users' printing activity, which they fear could lead to copyright lawsuits, if that data were shared with other companies looking to protect against 3D-printed spare parts, for example.
The bill in question is AB 2047, the scope of which, on paper, appears strict. The primary goal is clear and simple: to require 3D printer manufacturers to use a state-certified algorithm that checks digital design files for firearm components and blocks print jobs that would produce prohibited parts.
Federal law does not impose a blanket ban on making firearms for personal use, though ghost guns are subject to various federal and state restrictions, and the practice remains controversial nationwide.
Gun crime rates in the US far outweigh those in all other developed countries, so introducing legislation to curb the easy manufacture of untraceable firearms will be seen as a positive initiative to many, particularly in regions where guns are more strictly regulated.
However, Cliff Braun and Rory Mir, who respectively work in policy and tech community engagement at the EFF, claim that the proposals in California are technically infeasible and in practice will lead to consumer surveillance.
In a series of blog posts published this month, the pair argued that print-blocking technology - proposals for which have also surfaced in states including New York and Washington - cannot work for a range of technical reasons.
They argued that because 3D printers and other types of computer numerical control (CNC) machines are fairly simple, with much of their brains coming from the computer-aided manufacturing (CAM) software – or slicer software – to which they are linked, the bill would establish legal and illegal software. Proprietary software will likely become the de facto option, leaving open source alternatives to rot.
"Under these proposed laws, manufacturers of consumer 3D printers must ensure their printers only work with their software, and implement firearm detection algorithms on either the printer itself or in a slicer software," wrote Braun earlier this month.
"These algorithms must detect firearm files using a maintained database of existing models. Vendors of printers must then verify that printers are on the allow-list maintained by the state before they can offer them for sale.
"Owners of printers will be guilty of a crime if they circumvent these intrusive scanning procedures or load alternative software, which they might do because their printer manufacturer ends support."
Braun also argued that it would be trivial for anyone who uses 3D printers to make small tweaks to either the visual models of firearms parts, or the machine instructions (G-code) generated from those models, to evade detection.
Mir further argued that the bill offers no guardrails to keep this "constantly expanding blacklist" limited to firearm-related designs.
In his view, there is a clear risk that this approach will creep into other forms of alleged unlawful activity, such as copyright infringement.
"This could look like Nintendo blocking a Pikachu toy, John Deere blocking a replacement part, or even patent trolls forcing the hand of hardware companies," wrote Mir. "Repressive regimes, here or abroad, could likewise block the printing of 'extreme' and 'obscene' symbols, or tools of resistance like popular anti-ICE community whistles."
Braun and Mir have a list of other arguments against the bill. They say the algorithms are more than likely to lead to false positives, which will prevent good-faith users from using their hardware.
Many 3D printer owners also have no interest in printing firearm components. Most simply want the freedom to print trinkets and spare parts while others use them to print various items and sell them as an income stream.
That said, Gun Owners of California also opposes the bill, arguing that it does not target criminals, only innocent consumers and businesses.
"Californians deserve policies that focus on criminal misuse – not sweeping mandates that expand bureaucracy and restrict lawful activity," it wrote in a response to the bill's introduction in February.
Addressing the community behind 3D printer manufacturer and slicer provider Prusa Research, community manager Tommy Muszynski said the company is keeping a close eye on developments.
"At Prusa, safety is obviously the highest priority," he said in a comment on Reddit. "We want everyone to have a safe experience in this hobby, but at the same time, we have always been firm believers in the 'right to repair' and the right for you to use the machine you bought however you see fit.
"We've built our community on open source principles and the idea that your printer is a tool for your own creativity, not a device that should be locked down or surveilled." ®