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Assault weapons are designed for the battlefield and pose a serious public safety risk, making it easier for shooters to kill more people more quickly.  

In the past decade, shooters armed with assault weapons have wreaked havoc in our nation’s public spaces, from movie theaters and schools to churches, festivals, and city streets. These civilian versions of weapons created for the military are designed to kill humans quickly and efficiently. In the absence of federal legislation regulating assault weapons, states must take it upon themselves to protect their residents from these deadly weapons.


MEMO: Regulating Assault Weapons under the National Firearms Act

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Assault weapons are a class of semi-automatic firearm specifically designed to kill humans quickly and efficiently. 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, certain “semiautomatic assault weapons” were banned at the federal level, but currently there is no federal law regulating these highly lethal 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. Because of this lethality, assault weapons are frequently the guns of choice for individuals who carry out horrific public attacks.

  • 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. 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 mass shooting deaths.5
  • 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.6
  • 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.7

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 “unlawful for a person to manufacture, transfer, or possess” a semiautomatic assault weapon.8 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 banned 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.9 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.10 Additional information is available in our summary on Large Capacity Magazines.


We’re in this together. To build a safer America—one where children and parents in every neighborhood can learn, play, work, and worship without fear of gun violence—we need you standing beside us in this fight.

LOWER likelihood of mass shooting deaths
While the federal assault weapons ban was in effect, mass shooting fatalities were 70% less likely to occur.


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.

As described above, studies show that the federal assault weapons ban resulted in a marked decrease in the use of assault weapons and large capacity ammunition magazines in crime. 

The 1994 act did suffer from notable limitations, however. The two-feature test and the inclusion of some purely cosmetic features created a loophole that allowed manufacturers to successfully circumvent the law by making minor modifications to the weapons they already produced. The law also did not prohibit the continued transfer or possession of assault weapons manufactured before the law’s effective date. Manufacturers took advantage of this loophole by boosting production of assault weapons in the months leading up to the ban, creating a legal stockpile of these guns.

The Ban on the Importation of Non-Sporting Firearms and Their Parts

Federal law prohibits any person from importing a firearm unless authorized by the US attorney general.11 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.”12 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.13

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.”14 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.”15

Summary of State Law

Seven states and the District of Columbia have enacted laws banning assault weapons

California, Connecticut, Hawaii, Maryland, Massachusetts, New Jersey, New York, and the District of Columbia prohibit assault weapons. The earliest of these assault weapon restrictions was enacted in the District of Columbia as part of a 1932 federal law, with the remainder of states first adopting legislation to prohibit assault weapons later in the 20th century.16 In addition, Minnesota and Virginia regulate assault weapons.17

Assault weapons bans can be categorized according to:

  1. The definition(s) of “assault weapon”
  2. The activities that are prohibited
  3. Whether pre-ban weapons are exempted
  4. Whether exempted pre-ban weapons (legacy weapons) must be registered
  5. How transportation, transfer, and possession of legacy weapons are treated
State Assault Weapons Bans
StateList Banned by NameGeneric Feature DefinitionRequires Registration of Legacy WeaponsProhibits Transfer of Legacy Weapons
Other Regulation of Legacy Weapons
District of Columbia20YesYes
Hawaii22 (assault pistols only)NoYes
Yes (license)
New Jersey26YesNo27YesNo
Yes (license)
New York28NoYes

States that Regulate (But Do Not Ban) Assault Weapons

  • Minnesota29
  • Virginia30

Description of State Laws Banning Assault Weapons

Some state assault weapons bans prohibit specific weapons by listing them by name. Some state assault weapons bans list features that, when present, qualify a gun as an assault weapon. The latter are known as generic feature tests. Generic feature tests—emphasizing high capacity and enhanced control during firing—are intended to identify assault weapons based on the military features that enhance a weapon’s lethality. Generic feature tests requiring a weapon to have only one of a list of features are more comprehensive than those that require two. A one-feature test captures more assault weapons and makes it harder for the gun industry to evade the law by slightly modifying banned weapons.

California, Connecticut, New York, and the District of Columbia have the most comprehensive approaches to defining assault weapons. California law bans roughly 75 assault weapon types, models, and series by name and provides a one-feature generic test for rifles and pistols.31 Connecticut bans roughly 70 assault weapon types, models, and series by name and uses a one-feature generic test for rifles and pistols. The District of Columbia includes a list of assault weapon types, models, and series by name that closely follows the California list, and provides a one-feature generic test for rifles, pistols, and shotguns. The District also allows its Chief of Police to designate a firearm as an assault weapon based on a determination that the firearm would pose the same or similar danger to the residents of the District as other assault weapons. New York has adopted a one-feature test for assault pistols, shotguns, and rifles.

New Jersey bans roughly 65 assault weapon types, models, and series and copies of those weapons by name and uses a one-feature generic test for shotguns.32 Connecticut and New Jersey also ban parts that may be readily assembled into an assault weapon.

The generic feature tests in other bans, including the expired federal ban, are two-feature tests. Massachusetts law uses the definition of “assault weapon” from the expired federal law, including both the two-feature test and the federal law’s list of banned weapons. Hawaii only bans assault pistols, not assault rifles or shotguns, and uses the two-feature definition from the federal law, but does not include a list of named weapons. Maryland uses its own two-feature test and list of named weapons.

Prohibited Activities

Assault weapons bans vary as to which activities are prohibited. California prohibits the broadest range of activities. Both California and Connecticut prohibit possession, distribution, importation, transportation, and keeping or offering for sale of assault weapons.33 In addition, California prohibits the manufacture and transfer of assault weapons, while Connecticut also prohibits giving an assault weapon to another person. New Jersey and New York laws prohibit the manufacture, transportation, sale, shipping, transfer, disposing, and possession of assault weapons. Maryland prohibits the possession, sale, offering for sale, transfer, purchase, receipt, or transportation of assault weapons into the state.

Legacy Weapons Owned Prior to a Ban

deadliest mass shootings involved assault weapons
Assault weapons were used in the seven deadliest mass shootings of the last decade. Designed for combat, assault weapons enable shooters to kill more people more quickly.


Based on data compiled by Giffords Law Center. Last updated July 2020.

Assault weapons bans differ in their treatment of pre-ban weapons. The District of Columbia does not allow the possession of pre-ban weapons. Every state with a ban has legacy provisions that exempt pre-ban weapons, meaning that individuals who possessed prohibited assault weapons prior to the ban may generally keep them—provided that certain requirements are met. California, Connecticut, Hawaii, New Jersey, and New York, for example, require registration of such weapons.34 New Jersey’s law is particularly strong because only assault weapons with a legitimate target-shooting purpose may be registered (effectively requiring over 60 models, types and series of assault weapons to be transferred out of state, rendered inoperable, or surrendered to law enforcement). Maryland required registration of legacy assault pistols but not assault long guns. See our summary on the Registration of firearms for further information about registration systems.

California, Connecticut, Hawaii, Maryland, and New York prohibit transfer of all or most legacy weapons owned prior to the adoption of a ban. Only California and Connecticut 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.

The Takings Clause

Bans on assault weapons—whether they contain legacy provisions or not—do not present a problem under The Takings Clause of the Fifth Amendment.

The Second Amendment

Assault weapons bans have been upheld again and again over the years in both state and federal courts.36 The notion that such laws violate the Second Amendment has been soundly rejected.


Gun violence is a complex problem, and while there’s no one-size-fits-all solution, we must act. Our reports bring you the latest cutting-edge research and analysis about strategies to end our country’s gun violence crisis at every level.

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State Regulations Governing Assault Weapons


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.


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.”

District of Columbia Tort Liability Law Governing Assault Weapons

The District of Columbia imposes strict tort liability on manufacturers, importers, and dealers of assault weapons for all direct and consequential damages that arise from injury or death due to the discharge of an assault weapon in the District (with limited exceptions).37

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

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 generic features that characterize assault weapons (California, Connecticut, New York, and the District of Columbia have the most comprehensive definitions).
  • Definition of assault weapon is based on a one-feature test (New York, the District of Columbia and Cook County, Illinois each use a one-feature test for shotguns, rifles, and pistols; New Jersey uses a one-feature test for shotguns; California and Connecticut use a one-feature test for rifles and pistols).
  • 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 (District of Columbia).
  • Definition extends to parts that may be readily assembled into an assault weapon (Connecticut and New Jersey).
  • Prohibited activities include possession, sale, purchase, transfer, loan, pledge, transportation, distribution, importation, and manufacture of assault weapons (California has the broadest prohibition).
  • Pre-ban weapons are not exempted from a ban and instead are to be rendered inoperable or removed from the jurisdiction (District of Columbia and Cook County, Illinois; New Jersey exempted only a small category of assault weapons).
  • Alternatively, if pre-ban weapons are exempted and treated as legacy weapons, there is a registration mechanism for legacy weapons, with strict limits on their transferability, use, and storage39 (California, Connecticut, Hawaii, New Jersey, New York).

  1. The Militarization of the US Civilian Firearms Market,” Violence Policy Center, June 2011,; 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. 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.[]
  7. “Gun Policy Remains Divisive, But Several Proposals Still Draw Bipartisan Support,” Pew Research Center, October 18, 2018,[]
  8. 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.[]
  9. 18 U.S.C. § 921(a)(30).[]
  10. 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).[]
  11. 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).[]
  12. 18 U.S.C. 925(d)(3).[]
  13. 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).[]
  14. 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), Previously, in 1989, ATF used this authority to limit the importation of certain semiautomatic assault rifles. Id. at 2.[]
  15. 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, “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.”[]
  16. 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); and New York (Nov. 1, 2000). The District of Columbia’s ban dates back 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).[]
  17. In addition to having one of the country’s strongest assault weapons bans, Connecticut also prohibits the sale or retail transfer of any semi-automatic centerfire rifle that has or accepts a magazine with a capacity exceeding five rounds to any person under 21 years of age.  Conn. Gen. Stat. § 29-37a(b)(2).[]
  18. Cal. Penal Code §§ 16350, 16790, 16890, 30500-31115.[]
  19. Conn. Gen. Stat. §§ 53-202a – 53-202o.[]
  20. DC Code Ann. §§ 7-2501.01(3A), 7-2502.02(a)(6), 7-2505.01, 7-2505.02(a), (c).[]
  21. The District of Columbia did not exempt pre-ban assault weapons.[]
  22. Haw. Rev. Stat. Ann. §§ 134-1, 134-4, 134-8.[]
  23. Md. Code Ann., Crim. Law §§   4-301 – 4-306; Md. Code Ann., Pub. Safety § 5-101(r).[]
  24. Maryland required the registration of assault pistols, which were banned in the state many years before Maryland banned assault long guns.[]
  25. Mass. Gen. Laws ch. 140, §§ 121, 122, 123, 131M.[]
  26. N.J. Stat. Ann. §§ 2C:39-1w, 2C:39-5, 2C:58-5, 2C:58-12, 2C:58-13.[]
  27. New Jersey does use a one-feature test for shotguns.[]
  28. N.Y. Penal Law §§ 265.00(22), 265.02(7), 265.10, 400.00(16-a).[]
  29. Minn. Stat. §§ 624.712, 624.713, 624.7131, 624.7132, 624.7141.[]
  30. 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.[]
  31. California’s definition of assault weapon also includes a semi-automatic, centerfire rifle, or pistol with a fixed magazine capacity exceeding 10 rounds; a semi-automatic, centerfire rifle less than 30 inches in length; and a semi-automatic shotgun with two listed features, or the ability to accept a detachable magazine, or a revolving cylinder.[]
  32. New Jersey also bans semi-automatic rifles with a fixed magazine capacity exceeding 15 rounds.[]
  33. In 2006 California amended its law to make possession of an assault weapon a public nuisance. Cal. Penal Code § 30800.[]
  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 be no way to determine the date an individual acquired possession of a banned weapon.[]
  35. California and Connecticut 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). 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. 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).[]
  37. D.C. Code Ann. §§ 7-2551.01 – 7-2551.03. In 2005, Congress passed and the President signed into law the Protection of Lawful Commerce in Arms Act (PLCAA). The PLCAA grants firearms dealers and others immunity from some civil lawsuits, with certain exceptions. 15 U.S.C. §§ 7901 – 7903. For more information, see our page on Gun Industry Immunity.[]
  38. Cook County Code of Ordinances §§ 54-211 – 54-213.[]
  39. See our summary on the Registration for features of comprehensive registration laws. The most comprehensive system of regulating the purchase, possession and ownership of firearms combines registration of firearms with licensing of gun owners. Additional information on licensing of firearm owners is contained in our summary on Licensing.[]