All firearms leave markings on the cartridge cases they expel when fired.1  Ballistic identification and microstamping laws make it possible to link cartridge cases recovered at crime scenes to the firearm that fired them. Comprehensive ballistic identification systems (sometimes called ballistic “fingerprinting”) require gun manufacturers to test-fire the firearms they produce and store images of the ballistic markings left on cartridge cases in a database so that law enforcement can later determine whether a particular gun fired a particular cartridge. Microstamping is a newer technology that utilizes lasers to make precise, microscopic engravings on the internal mechanisms of a semiautomatic pistol, such as the breech face and firing pin. When the gun is fired, a unique alpha-numeric code identifying the gun’s make, model and serial number is stamped on to the cartridge case.2

Both ballistic identification and microstamping systems help law enforcement investigate gun crimes because cartridge cases are much more likely to be recovered at the scene of a shooting than the gun itself.3  These systems can identify the gun from which a cartridge case was fired without recovering the gun.4 Microstamping systems are more efficient, however, because they rely on intentional alpha-numeric codes unique to each firearm.

Ballistic Identification

In the mid-1990s, the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) pioneered the concept of using automated ballistic imaging and comparison equipment to analyze crime gun evidence.5  ATF’s National Integrated Ballistic Information Network (NIBIN) currently provides Integrated Ballistic Identification System (IBIS) equipment to numerous state and local law enforcement agencies nationwide.6  IBIS equipment is used to compare images of bullets and cartridge cases found at crime scenes to ballistic images previously entered into the NIBIN database.  When a “match” is found, firearms examiners are able to conclude that the same gun was used in both crimes.  Recovered crime guns are also test-fired and their ballistic images entered into the system, allowing law enforcement to determine whether those guns were used in other crimes.

Regarding NIBIN, ATF has concluded that, “Numerous violent crimes involving firearms have been solved through use of the system, many of which would not have been solved without it.”7

Traditional ballistic identification systems like NIBIN have two limitations, however.  For one thing, they generally only contain ballistic fingerprints from bullets, cartridges cases, and guns recovered from crime scenes. A comprehensive ballistic identification law would require gun manufacturers to submit a test-fired bullet and cartridge case for every firearm produced.  In addition, a high level of technological skill is required to match bullets or cartridge cases to a firearm based solely on ballistic fingerprints, meaning that the use of ballistic fingerprinting requires the involvement of trained firearms examiners.


Microstamping gives law enforcement a significant new investigative tool to solve gun-related crimes.8 When a cartridge case has been engraved with a code through microstamping, the code allows law enforcement to connect the cartridge case directly to the gun that fired it, much like the license plate on a vehicle allows law enforcement to identify the vehicle’s make, model and VIN number.  Studies have shown that semi-automatic pistols equipped with microstamping technology produce a significant amount of ballistic evidence that would not be produced if the pistol did not include the technology.9

In addition to assisting in the investigation and prosecution of gun crimes, this cutting-edge technology will deter gun trafficking.  Traffickers often purchase guns intending to transfer them to someone else illegally.  A trafficker who purchases a gun for this purpose would be on notice that the cartridge case could be used to trace the gun back to him or her if the gun was used in the commission of a crime.

In 2010, the American Bar Association (ABA) recommended that federal, state, and territorial governments enact microstamping laws that would enable law enforcement officers to identify the weapon used in a crime and the purchaser of that firearm.10 The ABA concluded, “Microstamping technology will be a material aid to law enforcement in the effort to solve crimes committed by use of guns.”11

Similarly, the International Association of Chiefs of Police (IACP) issued a resolution in 2008 supporting the use of microstamping technology in criminal investigations. The IACP specifically identified microstamping as an inexpensive yet effective way to mark and identify cartridge cases.12 The IACP concluded that this technology would help law enforcement to identify the purchaser of a weapon used in crime, therefore “providing leads that would allow for substantial evidentiary information that will help identify, apprehend and arrest criminals.”13

California was the first state to adopt a law requiring handguns to be equipped with microstamping technology, as described below.  That law went into effect on May 17, 2013.14

There is strong public support for ballistic identification and microstamping laws. A national poll conducted for Mayors Against Illegal Guns in the spring of 2008 found that 77% of Americans favor requiring all guns sold in the U.S. to have a ballistic fingerprint, which allows police to determine what gun fired a bullet.15

Ammunition serialization is another law enforcement tool that can assist in solving more gun-related crimes. For more information about ammunition serialization, see our summary on Ammunition Regulations.

For information about how law enforcement may identify the owner or purchaser of a firearm after determining that the firearm was used in a shooting, see our summary on Maintaining Records and Reporting Gun Sales.


Summary of Federal Law

Federal law does not require or address ballistic identification or microstamping technology.


Summary of State Law

California and the District of Columbia have adopted microstamping requirements for handguns. Maryland has created a statewide ballistics imaging database for new handguns sold in state, and Connecticut operates a statewide firearms evidence databank that stores ballistic information on handguns recovered or used by police.

Description of State Laws Governing Microstamping and Ballistic Identification

1.         Microstamping Requirements:         

California:  With legislation passed in 2007, California became the first state to require the use of handgun microstamping, an innovative technology that enables law enforcement to match cartridge cases found at a crime scene to the gun’s owner.  On October 13, 2007, Governor Arnold Schwarzenegger signed into law the Crime Gun Identification Act, which requires all new models of  semiautomatic pistols manufactured or sold in California to be designed and equipped with microstamping technology. The law required the California Department of Justice (DOJ) to certify when microstamping technology was available to more than one manufacturer unencumbered by patent restrictions; as noted above, DOJ made this certification in May 2013.16

The District of Columbia – Beginning January 1, 2016, the District will prohibit any licensed dealer from selling or offering for sale any semiautomatic pistol manufactured on or after January 1, 2016 that is not “microstamp-ready.” “Microstamp-ready” means a semiautomatic pistol that is manufactured to produce a unique alpha-numeric or geometric code on at least two locations on each expended cartridge case that identifies the make, model, and serial number of the pistol. Beginning January 1, 2016, a semiautomatic pistol must be microstamp-ready if it is:

  • Manufactured in the District of Columbia;
  • Manufactured on or after January 1, 2016, and delivered or caused to be delivered by any manufacturer to a firearms dealer in the District; or
  • Manufactured on or after January 1, 2016, and sold, offered for sale, loaned, given or transferred by a firearms dealer in the District.

A semiautomatic pistol manufactured after January 1, 2016, that is not microstamp-ready and that was acquired outside of the District by a person who was not a District resident at the time but who subsequently moved to the District is allowed, and may be sold, transferred, or given away, but only through a licensed firearms dealer.

In addition, beginning January 1, 2013, a manufacturer transferring a pistol to a firearms dealer for sale in the District will be required to certify whether the pistol was manufactured on or after January 1, 2016, and, if it was, that:

  • The pistol will produce a unique alpha-numeric code or a geometric code on each cartridge case that identifies the make, model, and serial number of the semiautomatic pistol that expended the cartridge case; and
  • The manufacturer will supply the Chief of Police with the make, model, and serial number of the pistol that expended the cartridge case, when presented with an alpha-numeric or geometric code from a cartridge case, provided that the cartridge case was recovered as part of a legitimate law enforcement investigation.17

2.         Traditional Ballistic Identification Requirements:

Maryland:  Maryland requires manufacturers to test-fire all handguns shipped into the state after October 1, 2000, and provide a spent cartridge case to the purchasing firearms dealer.  Once the gun is sold, the dealer must forward the case to the state police, who then enter its unique markings in a database for possible use in future criminal investigations.18

Connecticut:  Connecticut requires the Division of Scientific Services (“Division”) of the Connecticut Department of Emergency Services and Public Protection to establish a firearms evidence databank.  The databank is a computer-based system that stores images of fired components of ammunition in a manner suitable for retrieval and comparison to images of other fired components of ammunition stored in the databank.  Handguns recovered by police through a criminal investigation may be submitted to the Division laboratory for test firing and collection of fired components of ammunition.  Police departments are also required to submit all handguns issued to employees for test firing and collect fired components of ammunition from the test fire.19

New York repealed its ballistic identification requirements in 2012.20

50 State Summary


Key Legislative Elements

The features listed below are intended to provide a framework from which policy options may be debated.  A jurisdiction considering new legislation should consult with counsel.

  • Licensed firearms dealers in the jurisdiction are prohibited from selling or offering for sale any semiautomatic pistol unless it microstamps (District of Columbia; California requires any new model of semiautomatic pistol to microstamp)
  • A semiautomatic pistol “microstamps,” as the relevant term(s) is defined,  if it was manufactured to produce a unique alpha-numeric or geometric code on at least two locations on each expended cartridge case that identifies the make, model, and serial number of the pistol (California, District of Columbia)
  • Manufacturing a semiautomatic pistol that does not microstamp is prohibited in the jurisdiction (District of Columbia; California prohibits manufacturing a new model of semiautomatic pistol unless it microstamps)
  • Manufacturing a semiautomatic pistol that does not microstamp and offering it for sale or delivering it to a dealer in the  jurisdiction is prohibited (District of Columbia; California imposes this prohibition on new models of semiautomatic pistols)
  • Manufacturers must certify that each semiautomatic pistol transferred to a dealer in the jurisdiction microstamps (District of Columbia)
  • Manufacturers must supply law enforcement with the make, model, and serial number of the semiautomatic pistol that expended a cartridge case when presented with an alpha-numeric or geometric code from the cartridge case (District of Columbia)
  • Alternatively, manufacturers are required to provide ballistic identification for all new handguns manufactured or sold in the jurisdiction, and dealers are required to submit that information to state law enforcement when the gun is sold (Maryland)
    • For other weapons of particular concern to law enforcement, such as assault weapons and 50 caliber rifles, ballistic identification may also be required
    • In jurisdictions that require registration of handguns, current handgun owners are required to deliver their weapons to a ballistic testing center for purposes of ballistic identification to secure or maintain the registration21
  1. Robert M. Thompson et al., Ballistic Imaging and Comparison of Crime Gun Evidence by the Bureau of Alcohol, Tobacco and Firearms 4 (May 13, 2002). ⤴︎
  2. See Orest P. Ohar, Todd E. Lizotte, Extracting Ballistic Forensic Intelligence: Microstamped Firearms Deliver Data for Illegal Firearm Traffic Mapping – Technology 7434 Proc. of SPIE 743416 (2009), at http://csgv.org/wp/wp-content/uploads/2013/06/LIZOTTE-RESEARCH-PAPER-AUGUST-2009.pdf. ⤴︎
  3. See Coalition to Stop Gun Violence, Microstamping, at http://csgv.org/issues/microstamping/. ⤴︎
  4. The Educational Fund to Stop Gun Violence, Cracking the Case: The Crime-Solving Promise of Ballistic Identification 2 (July 2004). ⤴︎
  5. National Integrated Ballistic Information Network, Bureau of Alcohol, Tobacco and Firearms, U.S. Department of Treasury, The Missing Link: Ballistics Technology That Helps Solve Crimes 6-7 (2001). ⤴︎
  6. Thompson, supra note 1, at 4. ⤴︎
  7. Id. at 2. For example, on July 10, 2007, a gunman shot and killed three people in their apartment in North Charleston, South Carolina. Investigators used NIBIN to determine that the gun used had also been fired several months previously outside a nearby bar.  The bouncer at the bar was able to identify the person who had fired the gun at that time. Corroborating evidence confirmed that the person was guilty of the triple murder, and he was subsequently convicted. Bureau of Alcohol, Tobacco, Firearms & Explosives, NIBIN Success Story from the Charlotte Field Division, Triple Murder Solved with NIBIN, at http://www.atf.gov/content/Firearms/firearms-enforcement/NIBIN/success-stories/triple-murder-solved-with-NIBIN#overlay-context=content/NIBIN-helps-nab-multi-state-armed-robbery-suspects. ⤴︎
  8. See Orest P. Ohar, Todd E. Lizotte, Extracting Ballistic Forensic Intelligence: Microstamped Firearms Deliver Data for Illegal Firearm Traffic Mapping – Technology 7434 Proc. of SPIE 743416 (2009), at http://csgv.org/wp/wp-content/uploads/2013/06/LIZOTTE-RESEARCH-PAPER-AUGUST-2009.pdf. ⤴︎
  9. L.S. Chumbley et al., Clarity of Microstamped Identifiers as a Function of Primer Hardness and Type of Firearm Action, AFTE Journal Vol. 44, No. 2 145-155, 155 (Spring 2012); Todd E. Lizotte, Orest P. Ohar, Forensic Firearm Identification of Semiautomatic Handguns Using Laser Formed Microstamping Elements 7070 Proc. of SPIE 70700K (2008), at http://csgv.org/wp/wp-content/uploads/2013/06/FORENSIC-FIREARM-IDENTIFICATION-OF-SEMIAUTOMATIC-HANDGUNS-LIZOTTE.pdf. ⤴︎
  10. American Bar Association, Recommendation on Microstamping, 1 (Aug. 2010), AT http://csgv.org/wp/wp-content/uploads/2013/06/aba-resolution-on-microstamping-sept-10.pdf. ⤴︎
  11. Id. ⤴︎
  12. International Association of Chiefs of Police, Resolution: Support the Use of Microstamping Technology (Nov. 11, 2008). ⤴︎
  13. Id. ⤴︎
  14. Cal. Dept. of Justice, Firearms Bureau, Information Bulletin: Certification of Microstamping Technology (May 17, 2013), at http://oag.ca.gov/sites/all/files/agweb/pdfs/firearms/infobuls/2013-BOF-03.pdf. ⤴︎
  15. Greenberg Quinlan Rosner Research & the Tarrance Group for the Mayors Against Illegal Guns, Americans Support Common Sense Measures to Cut Down on Illegal Guns 6, (Apr. 10, 2008), at http://www.mayorsagainstillegalguns.org/downloads/pdf/polling_memo.pdf. ⤴︎
  16. Cal. Dept. of Justice, Firearms Bureau, Information Bulletin: Certification of Microstamping Technology (May 17, 2013), at http://oag.ca.gov/sites/all/files/agweb/pdfs/firearms/infobuls/2013-BOF-03.pdf.  If a method of equal or greater reliability and effectiveness in identifying the specific serial number of a pistol from spent cartridge cases discharged by that firearm exists, and is also unencumbered by patent restrictions, the law allows DOJ to approve it as well. Cal Pen Code § 31910. ⤴︎
  17. D.C. Code Ann. §§ 7-2504.08; 7-2505.03 (as amended by 61 D.C. Reg. 324 (Jan. 17, 2014) ). ⤴︎
  18. Md. Code Ann., Pub. Safety § 5-131. ⤴︎
  19. Conn. Gen. Stat. § 29-7h. ⤴︎
  20. 2012 N.Y. ALS 55, Part B, § 1. ⤴︎
  21. Additional information on registration of firearms is contained in our summary on the Registration of Firearms. ⤴︎