Assault weapons, especially assault rifles, are typically semiautomatic versions of weapons created for deadly battlefield purposes. They are designed and equipped with features that enable mass killing, including sustained, high-volume rapid fire shooting at large numbers of people in a short period of time. The availability of unusually dangerous weaponry like assault weapons and large-capacity magazines has fueled an alarming increase in high casualty mass shootings across the nation. Perpetrators of many of the deadliest shootings in modern American history—including in Las Vegas, Orlando, Sandy Hook Elementary School, Sutherland Springs, El Paso, Robb Elementary School, Marjory Stoneman Douglas High School, Aurora, and Dayton—used assault weapons equipped with large-capacity magazines. These unusually dangerous weapons also expose law enforcement officers to heightened risk from gunmen wielding increasingly high-powered combat grade weapons on civilian streets.

In the absence of federal legislation regulating assault weapons, states must take it upon themselves to protect their residents from mass shootings by regulating or banning the sale and manufacture of these uniquely dangerous weapons.

Background

MEMO: Regulating Assault Weapons under the National Firearms Act

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Assault weapons are typically a subset of semi-automatic firearms with features designed to enable shooters to repeatedly fire at large numbers of people quickly. They are a relatively new class of weapon—during the 1980s, the gun industry sought to reverse a decline in consumer demand for guns by developing and marketing new types of weapons based on high-powered military designs.¹ Between 1994 and 2004, a relatively narrow federal assault weapons law placed some restrictions on the sale and manufacture of some “semiautomatic assault weapons.” This federal law expired in 2004. Though the US House of Representatives passed legislation in 2022 to renew and strengthen this assault weapons law, that legislation has not passed the US Senate and there is currently no federal law restricting the sale, manufacture, or possession of assault weapons.

Wounds caused by assault weapons are more severe and lethal than wounds caused by other firearms, and, particularly when paired with large capacity magazines, assault weapons can injure more people more quickly.

• Assault weapons have been used in the seven deadliest mass shootings in the last decade.
• An analysis of public mass shootings resulting in four or more deaths found that more than 85% of such fatalities were caused by assault rifles.²
• An assailant with an assault rifle is able to hurt and kill twice the number of people compared to an assailant with a non-assault rifle or handgun.³

A growing body of research demonstrates that banning assault weapons can help to prevent gun violence, and mass shootings in particular. Studies of both the lapsed federal assault weapons ban and state-level assault weapons bans show that these laws help to reduce fatalities and injuries from mass shootings, as well as the use of assault weapons in crime.

• During the 10-year period the federal assault weapons ban was in effect, mass shooting fatalities were 70% less likely to occur compared to the periods before and after the ban.⁴
• Studies also suggest that state level assault weapons bans help to prevent gun violence.⁵ For example, when Washington passed an assault weapons ban for people under age 21, there were significant decreases in the number of firearm incidents with assault weapons by this group, as well as an overall decrease in firearm violence in the state. ⁶
• In several major cities, the share of recovered crime guns that were assault weapons declined by at least 32% after the federal ban was adopted.⁷
• Importantly, researchers have been able to demonstrate that the federal assault weapons ban prevented mass shootings and decreased the diversion of assault weapons to criminal use, despite limitations in law which allowed manufacturers to circumvent the regulations.

The American public strongly supports efforts to better regulate assault weapons. 67% of Americans— including half of all Republicans—support a ban on assault weapons.⁸

Summary of Federal Law

The Lapsed Federal Assault Weapons Ban

In 1994, Congress adopted the Violent Crime Control and Law Enforcement Act of 1994, which made it generally “unlawful for a person to manufacture, transfer, or possess” a semiautomatic assault weapon.⁹ The law was adopted with a sunset clause, however, and expired in 2004, despite overwhelming public support for its renewal. Thus, semi-automatic, military style weapons that were formerly regulated under federal law are now legal unless banned by state or local law.

The 1994 act defined the phrase “semiautomatic assault weapon” to include 19 named firearms and copies of those firearms, as well as certain semi-automatic rifles, pistols, and shotguns with at least two specified characteristics from a list of features.¹⁰ The full “semiautomatic assault weapon” definition from the 1994 act is available here. The federal ban also prohibited the transfer and possession of any new large capacity ammunition magazine.¹¹ Additional information is available in our summary on Large Capacity Magazines.

Ban on Importation of Non-Sporting Firearms

Federal law prohibits any person from importing a firearm unless authorized by the US attorney general.¹² The attorney general must authorize the importation of any firearm that “is generally recognized as particularly suitable for or readily adaptable to sporting purposes, excluding surplus military firearms.”¹³ Federal law also prohibits any person from assembling from imported parts any semiautomatic rifle or any shotgun which is identical to any rifle or shotgun prohibited from importation.¹⁴

In 1998, ATF announced that semiautomatic rifles capable of accepting large capacity ammunition magazines “are not generally recognized as particularly suitable for or readily adaptable to sporting purposes and are therefore not importable.”¹⁵ However, a 2011 report by three US Senators found that, “Since the Clinton Administration’s efforts, the Gun Control Act of 1968’s prohibition against non-sporting firearms has not been aggressively enforced, and many military-style, non-sporting rifles have flowed into the United States civilian market.”¹⁶

Summary of State Law

TEN states and the District of Columbia have enacted laws broadly restricting assault weapons

Ten states (California, Connecticut, Delaware, Hawaii, Illinois, Maryland, Massachusetts, New Jersey, New York, and Washington), as well as the District of Columbia, have enacted laws that generally ban the sale, manufacture, and transfer of assault weapons. Two other states (Minnesota and Virginia) have also enacted laws that place some additional safety requirements and regulations on assault weapons, though these regulations fall far short of the general ban on the sale and manufacture of assault weapons enacted in the other nine states above.

The earliest assault weapon restrictions were enacted in the District of Columbia as part of a 1932 federal law, with the remaining nine states first adopting legislation to prohibit assault weapons later in the 20th century, starting with California.¹⁷

While many state assault weapon laws are broadly similar, there are significant differences regarding:

1. Which firearms are classified as restricted “assault weapons”
2. How much conduct does the state regulate or prohibit with those restricted assault weapons (e.g., sale, manufacture, possession)
3. What exemptions apply to legacy assault weapons acquired before the assault weapon law went into effect
4. Did state law require owners of legacy assault weapons to submit information to record or “register” their firearm with law enforcement
5. Are there other rules governing how and where authorized owners may use or carry assault weapons

States that Regulate (But Do Not Generally Ban) Assault Weapons

• Minnesota³²
• Virginia³³

Deeper dive into State Assault Weapon laws

Some state laws regulating assault weapons have used much stronger definitions of “assault weapon” than others, applying these safety protections and restrictions to a broader subset of firearms.

Some have defined firearms as restricted assault weapons by referencing a list of specific named firearm models and weapons that are determined to be duplicates or “copycats” of those named firearm models.

Some states have (either additionally or instead) used a “characteristics” or “features” test that designates firearms as restricted assault weapons if they combine a certain number of features that make the firearm most useful for assaultive purposes, including features that provide high-volume firing capacity, enhanced control when the firearm is rapidly repeatedly fired, enhanced weapon concealability, and other features such as flash suppressors and grenade launchers that may be indicative of assaultive purposes. For example, many state assault weapon laws state that the definition of restricted “assault weapon” includes semiautomatic rifles that have a fixed magazine capable of accepting more than 10 rounds of ammunition, or semiautomatic rifles that combine the ability to accept detachable magazines with at least one other assaultive feature. Some of the narrower and weaker state assault weapons laws define firearms as assault weapons only if they combine a larger number of these assaultive features. A one-feature test includes more assault weapons and helps prevent the gun industry from skirting the law by selling very slightly modified versions of banned weapons.

Prohibited Activities

Assault weapons bans vary in what conduct is regulated. Some state laws like California broadly restrict sale, offer for sale, manufacture, distribution, importation, transportation, and keeping or offering for sale of assault weapons. The strongest laws also generally prohibit possession of assault weapons too, including strong regulation of legacy weapons acquired before the assault weapon law was enacted. For example, California and Illinois generally require people who owned legacy assault weapons prior the assault weapons law’s enactment to record or register their weapon with state law enforcement and possess that weapon only in specified locations or circumstances on private property, at shooting ranges, or while engaged in lawful hunting activity.

Legacy Weapons Acquired Prior to Assault Weapons Ban

California, Connecticut, Hawaii, Illinois, Maryland, and New York prohibit transfer of all or most legacy weapons owned prior to the adoption of a ban. California, Connecticut, and Delaware limit the places where a legacy weapon may be possessed.³⁵ In Massachusetts and New Jersey, legacy weapons may only be sold and possessed if the owner has a license. Additional information on licensing of firearm owners is contained in our summary on Licensing.

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States regulating but not banning Assault Weapons

Minnesota

Minnesota prohibits the possession of “semiautomatic military-style assault weapons” by persons under 18 years of age, as well as other prohibited persons, and imposes additional restrictions on transfers through firearms dealers. As of August 1, 2023, Minnesota will require semiautomatic military-style assault weapon purchasers to obtain a transferee permit unless the purchaser is purchasing from or transacting the sale through a federally licensed dealer.³⁶ A concealed carry permit constitutes a transferee permit for the purpose of purchasing an assault weapon.³⁷

Virginia

Virginia limits the knowing and intentional possession and transportation of certain semi-automatic “assault firearms” to citizens and permanent residents age 18 and older. These weapons may not be carried, loaded, in public places in certain cities and counties. Virginia also imposes a general ban on the importation, sale, possession, and transfer of the “Striker 12” and semi-automatic folding stock shotguns of like kind, but does not refer to them as “assault firearms.”

Selected Local Law

Cook County, Illinois 

Adopted by Cook County, Illinois, in 1993, the Blair Holt Assault Weapons Ban prohibits the manufacture, sale, transfer, or possession of an assault weapon or large capacity magazines in Cook County, Illinois. The Ban was adopted in 1993, but was amended and renamed in memory of Blair Holt, a 16-year-old boy who was shot and killed as a bystander when gang violence erupted on a bus in 2007. The law includes an extensive list of prohibited assault weapon types, models, and series, and provides a one-feature test identifying other rifles, shotguns, and pistols as assault weapons. The law defines a large capacity magazine as any ammunition feeding device with the capacity to accept more than ten rounds. The 1993 ordinance enacting this law provided that any person who was legally in possession of an assault weapon or large capacity magazine at that time had 90 days to: (1) remove it from the county; (2) modify it so it was rendered either inoperable or so changed that it would fall outside the definition of “assault weapon” or “large capacity magazine;” or (3) surrender it to law enforcement. Only law enforcement officers and members of the military are now allowed to possess assault weapons or large capacity magazines in the county.³⁸

Courts Have Repeatedly Supported Assault Weapons Bans

Assault weapons bans have been upheld again and again over the years in both state and federal courts.³⁹

The US Supreme Court has repeatedly recognized the nation’s clear “historical tradition of prohibiting the carrying of ‘dangerous and unusual weapons’” for the purpose of protecting public safety.⁴⁰ The Court indicated that bans on dangerous and unusual “weapons that are most useful in military service” are “presumptively lawful regulatory measures,”⁴¹ and emphasized that in our nation’s historical record, “[f]rom Blackstone through the 19^th-century cases, commentators and courts routinely explained that the [Second Amendment] right was not a right to keep and carry any weapon whatsoever in any manner whatsoever and for whatever purpose.”⁴² Restrictions on uniquely dangerous weaponry like assault weapons do not substantially burden individuals’ right or ability to defend themselves with a firearm. Instead, they reduce shooters’ capacity to inflict mass murder and to chill the exercise of other fundamental rights.

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Key Legislative Elements

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

• Definition of assault weapon is based on the features that characterize assault weapons
• Definition of assault weapon is based on a one-feature test
• Although a generic feature test is the most comprehensive approach, if the law also includes a list of banned weapons by name, it provides a mechanism authorizing an appropriate governmental official or agency to add new and/or modified models to the list
• Definition extends to parts that may be readily assembled into an assault weapon
• Prohibited activities include possession, sale, purchase, transfer, loan, transportation, distribution, importation, and manufacture of assault weapons
• Legacy weapons must be registered, securely stored when not in use, and used only in specific authorized locations such as the owner’s private property and shooting ranges.

1. The Militarization of the US Civilian Firearms Market,” Violence Policy Center, June 2011, http://www.vpc.org/studies/militarization.pdf; Christopher S. Koper, Daniel J. Woods, and Jeffrey A. Roth, “An Updated Assessment of the Federal Assault Weapons Ban: Impacts on Gun Markets and Gun Violence, 1994–2003,” National Institute of Justice, US Department of Justice, June 2004.[↩]
2. Charles DiMaggio et al., “Changes in US Mass Shooting Deaths Associated with the 1994–2004 Federal Assault Weapons Ban: Analysis of Open–source Data,” Journal of Trauma and Acute Care Surgery 86, no. 1 (2019): 11–19.[↩]
3. Elzerie de Jager, et al., “Lethality of Civilian Active Shooter Incidents With and Without Semiautomatic Rifles in the United States,” JAMA 320, no. 10 (2018): 1034–1035.[↩]
4. Charles DiMaggio et al., “Changes in US Mass Shooting Deaths Associated with the 1994–2004 Federal Assault Weapons Ban: Analysis of Open–source Data,” Journal of Trauma and Acute Care Surgery 86, no. 1 (2019): 11–19.[↩]
5. See, e.g., Mark Gius, “The Impact of State and Federal Assault Weapons Bans on Public Mass Shootings,” Applied Economics Letters 22, no. 4 (2015): 281–284; Arindrajit Dube, Oeindrila Dube, and Omar García-Ponce, “Cross–border Spillover: US Gun Laws and Violence in Mexico,” American Political Science Review 107, no. 3 (2013): 397–417.[↩]
6. Bhullar et al., “Washington State Assault Weapon Firearm Violence Before and After Firearm Legislation Reform,” The American Surgeon, (2024).[↩]
7. Christopher S. Koper, Daniel J. Woods, and Jeffrey A. Roth, “An Updated Assessment of the Federal Assault Weapons Ban: Impacts on Gun Markets and Gun Violence, 1994–2003,” National Institute of Justice, US Department of Justice, June 2004.[↩]
8. “Gun Policy Remains Divisive, But Several Proposals Still Draw Bipartisan Support,” Pew Research Center, October 18, 2018, https://pewrsr.ch/2P8uH5t.[↩]
9. 18 U.S.C. § 922(v)(1). All references to sections of the Violent Crime Control and Law Enforcement Act of 1994, codified at 18 U.S.C. § 921 et seq., are to the sections as they appeared on September 12, 2004.[↩]
10. 18 U.S.C. § 921(a)(30).[↩]
11. 18 U.S.C. §§ 921(a)(31), 922(w)(1). The federal law defined “large capacity ammunition feeding device” as “a magazine, belt, drum, feed strip, or similar device…that has a capacity of, or that can be readily restored or converted to accept, more than 10 rounds of ammunition.” 18 U.S.C. § 921(a)(31)(A). However, “attached tubular device[s] designed to accept, and capable of operating only with, .22 caliber rimfire ammunition” were exempted from the definition. 18 U.S.C. § 921(a)(31)(B).[↩]
12. 18 U.S.C. §§ 922(l), 925(d)(3). Federal law also prohibits any person from knowingly receiving a firearm that was imported without authorization. 18 U.S.C. § 922(l).[↩]
13. 18 U.S.C. 925(d)(3).[↩]
14. 18 U.S.C. § 922(r). The law also prohibits the importation of “any frame, receiver, or barrel of such firearm which would be prohibited if assembled.” 18 U.S.C § 925(d)(3).[↩]
15. Bureau of Alcohol, Tobacco and Firearms, US Department of the Treasury, Department of the Treasury Study on the Sporting Suitability of Modified Semiautomatic Assault Rifles (Apr. 1998), http://www.atf.gov/files/publications/download/treas/treas-study-on-sporting-suitability-of-modified-semiautomatic-assault-rifles.pdf. Previously, in 1989, ATF used this authority to limit the importation of certain semiautomatic assault rifles. Id. at 2.[↩]
16. Senators Dianne Feinstein, Charles Schumer & Sheldon Whitehouse, Halting U.S. Firearms Trafficking to Mexico (Report to the U.S. Senate Caucus on Int’l Narcotics Control, 2011), 13, https://www.feinstein.senate.gov/public/_cache/files/b/e/beaff893-63c1-4941-9903-67a0dc739b9d/E735381490CD5962A57DE3BB6DDBBE6C.061011firearmstraffickingreport.pdf. “Many of the Romanian-manufactured AK-47s that found their way to Mexico have been imported into the United States from Europe as a whole firearm or in parts as a kit despite a US ban on the importation of semi-automatic assault rifles.” Goodman & Marizco, supra note 11, “U.S. Firearms Trafficking to Mexico.”[↩]
17. Laws prohibiting assault weapons in these states first became effective in this order: California (Jan. 1, 1990); New Jersey (Sept. 1, 1990); Hawaii (July 1, 1992, assault pistols only); Connecticut (Oct. 1, 1993); Maryland (June 1, 1994, assault pistols only, expanded to include long guns effective Oct. 1, 2013); Massachusetts (codification of federal assault weapons ban effective July 23, 1998, with new state licensing requirements effective Oct. 21, 1998); New York (Nov. 1, 2000); Delaware (June 30, 2022); Illinois (January 10, 2023); and Washington (April 25, 2023(. The District of Columbia’s ban dates to a 1932 federal law, re-codified by the District in 1975, which prohibited the possession of all semiautomatic firearms in the District of Columbia if they were capable of firing more than 12 rounds, which effectively included all semiautomatic firearms and assault weapons. See Act of July 8, 1932, ch. 465, §§ 1, 8, 47 Stat. 650, 650, 652; Firearms Control Regulations Act of 1975, D.C. Law 1-85. The District of Columbia relaxed this prohibition on semiautomatic firearms in 2009 while continuing to prohibit assault weapons. See 56 D.C. Reg. 3438 (May 1, 2009); D.C. Code §§ 7-2502.02(a)(6), 7-2501.01(3A)(A).[↩]
18. Cal. Penal Code §§ 16350, 16790, 16890, 30500-31115.[↩]
19. Conn. Gen. Stat. §§ 53-202a – 53-202o.[↩]
20. Del. Code tit. 11, § 1466(a).[↩]
21. DC Code Ann. §§ 7-2501.01(3A), 7-2502.02(a)(6), 7-2505.01, 7-2505.02(a), (c).[↩]
22. The District of Columbia did not exempt pre-ban assault weapons.[↩]
23. Haw. Rev. Stat. Ann. §§ 134-1, 134-4, 134-8.[↩]
24. See HB 5471, enacted January 10, 2023).[↩]
25. Md. Code Ann., Crim. Law §§   4-301 – 4-306; Md. Code Ann., Pub. Safety § 5-101(r).[↩]
26. Maryland required the registration of assault pistols, which were banned in the state many years before Maryland banned assault long guns.[↩]
27. Mass. Gen. Laws ch. 140, §§ 121, 122, 123, 131M.[↩]
28. N.J. Stat. Ann. §§ 2C:39-1w, 2C:39-5, 2C:58-5, 2C:58-12, 2C:58-13.[↩]
29. New Jersey does use a one-feature test for shotguns.[↩]
30. N.Y. Penal Law §§ 265.00(22), 265.02(7), 265.10, 400.00(16-a).[↩]
31. Rev. Code Wash. (ARCW) Chp. 9.41 as amended by 2023 HB 1240.[↩]
32. Minn. Stat. §§ 624.712, 624.713, 624.7131, 624.7132, 624.7141.[↩]
33. Va. Code Ann. §§ 18.2-287.4, 18.2-308.2:01, 18.2-308.2:2, 18.2-308.7, 18.2-308.8.[↩]
34. Registration is critical to any law that exempts pre-ban weapons. Without such a provision, it would be nearly impossible to enforce a possession ban because there would in too many cases be no easy way to determine the date an individual acquired possession of a banned weapon.[↩]
35. These states generally allow possession of a legacy assault weapon only at, or when being transported among: the possessor’s property or workplace; the property of an expressly-consenting owner; a licensed gun dealer (for service or repair); certain target ranges; licensed shooting clubs; or an exhibition, display or education project about firearms approved by law enforcement or a recognized firearm-education entity. Cal. Penal Code § 30945; Conn. Gen. Stat. § 53-202d(f); Del. Code tit. 11, § 1466(c)(3). California also allows possession of a legacy assault weapon on publicly owned land, provided it is specifically permitted by the managing authority. Cal. Penal Code § 30945.[↩]
36. Minn. Stat. § 624.7134, subds. 2 and 3.[↩]
37. Minn. Stat. § 624.7131, subd. 9.[↩]
38. Cook County Code of Ordinances §§ 54-211 – 54-213.[↩]
39. See, e.g., Kolbe v. Hogan, 849 F.3d 114 (4th Cir. 2017) (en banc) (Maryland’s assault weapons ban does not violate the Second Amendment), New York State Rifle & Pistol Ass’n v. Cuomo, 804 F.3d 242 (2d Cir. 2015) (New York and Connecticut laws prohibiting possession of semiautomatic assault weapons and large-capacity magazines do not violate the Second Amendment); Friedman v. City of Highland Park, 784 F.3d 406 (7th Cir. 2015) (upholding local ordinance prohibiting assault weapons and large capacity ammunition magazines); Heller v. District of Columbia (“Heller II”), 670 F.3d 1244, 1260-64 (D.C. Cir. 2011) (upholding the District of Columbia’s ban on assault weapons and large capacity ammunition magazines after applying intermediate scrutiny); Fyock v. City of Sunnyvale, 779 F.3d 991 (9th Cir. Mar. 4, 2015); Kampfer v. Cuomo, 993 F. Supp. 2d 188, at *17-19 & n.10 (N.D.N.Y Jan. 7, 2014) (upholding New York’s assault weapons ban by finding it does not substantially burden Second Amendment rights); People v. James, 174 Cal. App. 4th 662, 676-77 (2009) (upholding California’s ban on assault weapons and .50 caliber rifles).[↩]
40. See, e.g.,N.Y. State Rifle & Pistol Ass’n (2022), slip op. 3 (Kavanaugh, J., concurring); Heller, 554 U.S. at 626-27, and n. 26; United States v. Miller, 307 U. S. 174, 179 (1939).[↩]
41. Heller, 554 U.S. at 626-27, and n. 26.[↩]
42. N.Y. State Rifle & Pistol Ass’n (2022), slip op. 12; Heller, 554 U.S. at 626.[↩]