California AB 2047 Overview & Technical Solution

At a glance

Assembly Bill 2047, by Assemblymember Rebecca Bauer-Kahan, is the California Firearm Printing Prevention Act. Governor Gavin Newsom signed it on September 26, 2026, and it was chaptered as Chapter 461, Statutes of 2026. It adds Title 21.1 to the Civil Code (§§ 3273.631–3273.634).

The requirement: 3D printers sold in California must include “firearm blocking technology” that meets minimum performance standards set by the California Department of Justice (DOJ).
The trigger: DOJ sets those standards only after ASTM International publishes an industry standard showing that blocking is technologically feasible.
The start date: there is no fixed date. The sales requirement begins one year after DOJ publishes its guidance or regulations.

California is the second state, after New York, to put a 3D-printer blocking requirement into law. Both laws make the requirement depend on standards that do not exist yet.

What the law requires

The law defines firearm blocking technology as:

“hardware, firmware, or other integrated technological measures capable of ensuring a three-dimensional printer will not proceed to any print job unless the underlying three-dimensional printing file has been evaluated by a firearms blueprints detection algorithm and determined not to be a printing file that would produce a firearm or a machine gun conversion device.”

A machine gun conversion device is a part designed to convert a semiautomatic weapon into a machine gun, including a “pistol converter.” The final law does not define “firearms blueprints detection algorithm.” Earlier drafts did, but the Senate amendments removed those definitions, so the details are left to DOJ and the ASTM standard.

Starting one year after DOJ publishes its standards, two rules apply under § 3273.633(c):

Manufacturers must ensure each 3D printer is equipped with compliant blocking technology before they sell, offer to sell, or transfer it for consideration to any person or business in California.
Anyone is prohibited from selling, offering for sale, or transferring for consideration a 3D printer in California that lacks compliant blocking technology. That reaches retailers and resellers, not only manufacturers.

The law uses the existing Civil Code definition of a three-dimensional printer (§ 3273.60(d)): a computer-aided manufacturing device that builds an object from a digital model through an additive process, layering two-dimensional cross sections of resin or similar material. Subtractive machines such as CNC mills fall outside that definition.

The ASTM trigger

The requirement hinges on ASTM International, the standards body. Beginning no later than July 1, 2027, and every quarter after that, DOJ must check whether ASTM has published industry standards for equipping 3D printers with firearm blocking technology.

DOJ acts only if it finds that ASTM has published or adopted such standards and that “those standards demonstrate that it is technologically feasible to equip three-dimensional printers with firearm blocking technology.” If both are true, DOJ has 24 months to publish written guidance or regulations that:

set minimum performance standards for blocking technology, developed with stakeholders under the Administrative Procedure Act;
are informed by the ASTM standards and may incorporate some or all of them;
may add other definitions, standards, or requirements, and may draw on standards adopted by other states;
may, but need not, require manufacturers to self-certify that each printer make and model meets the standards.

If ASTM has not published standards by July 1, 2029, DOJ is no longer required to keep checking. The text does not say what happens if ASTM publishes a standard after that date.

Timeline

Feb 17, 2026Introduced in the Assembly.
May 26, 2026Passes the Assembly, 58–19.
Aug 31, 2026Passes the Senate as amended. The Assembly concurs, 60–18.
Sep 26, 2026Signed by the Governor and chaptered as Chapter 461, Statutes of 2026.
Jan 1, 2027Takes effect. It is not an urgency statute, so California’s default effective date applies.
By Jul 1, 2027DOJ begins quarterly checks for an ASTM blocking-technology standard.
Within 24 monthsDOJ publishes minimum performance standards, if ASTM’s standard shows blocking is feasible.
1 year after DOJThe sales requirement applies to 3D printers sold in California.
Jul 1, 2029If ASTM still has not published a standard, DOJ is no longer required to check.

Exemptions and enforcement

Entertainment props. The requirement does not apply to printers used exclusively to manufacture props for the entertainment industry.
Blocking-technology development. California’s existing civil liability for distributing digital firearm code (Civil Code § 3273.61) does not apply to distribution solely for developing, refining, and testing blocking technology, or for maintaining a library of firearm files for that purpose.
Further exceptions. DOJ may adopt more exceptions by regulation if they are consistent with the law’s purpose, and may update its standards as ASTM revises its own.

The new title sets no penalties of its own, names no enforcing agency, and creates no private right of action. Earlier versions included a $25,000-per-violation civil penalty and a private right of action, but the final Senate amendments removed them. The text also has no provisions on user privacy, data collection, or whether files are checked on the device or in the cloud.

How the bill changed before passage

The version that passed the Assembly in May set fixed deadlines. DOJ would have certified detection algorithms, published a list of compliant printers, and set accuracy standards for false positives and false negatives. A July 2026 Senate version set a sales ban starting December 1, 2029.

The August 28 Senate floor amendments replaced those deadlines with the ASTM trigger and the feasibility finding. They also made manufacturer self-certification optional, narrowed the exemptions to props and blocking-technology development, and removed the enforcement provisions.

What it means for 3D-printer makers

No standard exists yet, so no printer can be certified as compliant today. The ASTM process now matters more than any state deadline. Whatever ASTM publishes will shape DOJ’s performance standards, and likely New York’s too.

Manufacturers that sell in California can prepare by joining the ASTM work, testing how file screening fits their firmware and slicing software, and measuring false-positive rates on lawful mechanical parts. Those rates will decide whether blocking is practical for customers.

Where PrintGuard fits

AB 2047 describes technology that evaluates a print file and stops the job if it would produce a firearm or conversion device. PrintGuard v1 screens 3D-printing files for firearm geometry before they print. It runs locally on your infrastructure and records every decision for review.

Talk to us about AB 2047

Frequently asked questions

Does AB 2047 ban 3D printers in California?

No. It requires 3D printers sold in California to include firearm blocking technology that meets DOJ’s standards, once those standards exist.

When does AB 2047 take effect?

The law takes effect January 1, 2027, and DOJ must start checking for an ASTM standard by July 1, 2027. The printer sales requirement has no fixed date: it begins one year after DOJ publishes performance standards, which can only happen after ASTM publishes a standard showing blocking is feasible.

What is firearm blocking technology?

Hardware, firmware, or other integrated measures that stop a 3D printer from running any print job until the file has been checked by a firearms blueprint detection algorithm and found not to produce a firearm or machine gun conversion device.

What happens if ASTM never publishes a standard?

DOJ does not set standards and the sales requirement does not begin. If ASTM has not published one by July 1, 2029, DOJ is no longer required to keep checking.

Does AB 2047 apply to CNC machines?

No. It uses California’s existing definition of a three-dimensional printer, which covers additive machines that build objects layer by layer. New York’s law, by contrast, also reaches some subtractive machines.

Sources

This summary is informational and is not legal advice. Quotations are from the chaptered bill text. The January 1, 2027 effective date follows California’s default rule for non-urgency statutes; the bill does not state one. Last reviewed October 5, 2026.