Common Use Doctrine

Origin and Development

Historical Foundation

The Common Use Doctrine traces its roots to United States v. Miller (1939), where the Supreme Court suggested that the Second Amendment protects weapons that have "some reasonable relationship to the preservation or efficiency of a well regulated militia." This implied that military weapons in common use would be protected.

Modern Articulation in Heller

DC v. Heller (2008) reformulated this principle, stating:

"The Second Amendment extends, prima facie, to all instruments that constitute bearable arms, even those that were not in existence at the time of the founding... [but] the sorts of weapons protected were those 'in common use at the time.'"

— Justice Scalia, DC v. Heller, 554 U.S. 570, 582 (2008)

The Court explained that this limitation is "fairly supported by the historical tradition of prohibiting the carrying of 'dangerous and unusual weapons.'"

Clarification in Caetano

In Caetano v. Massachusetts (2016), the Supreme Court clarified that the relevant time for determining common use is the present, not 1791:

"The Court has held that 'the Second Amendment extends, prima facie, to all instruments that constitute bearable arms, even those that were not in existence at the time of the founding.'"

— Per Curiam Opinion, Caetano v. Massachusetts, 577 U.S. 411 (2016)

Defining Common Use

Three Key Elements

Courts have identified three primary factors in determining common use:

1. Numerical Prevalence: How many Americans own the weapon
2. Lawful Purpose: Whether the weapon is typically possessed for lawful purposes
3. Typical Possession: Whether law-abiding citizens typically possess such weapons

The "Lawful Purpose" Requirement

Heller emphasized that common use refers to weapons "typically possessed by law-abiding citizens for lawful purposes." This dual requirement means:

• The weapon must be numerically common
• It must be commonly used for lawful purposes (self-defense, sporting, etc.)
• Criminal use alone cannot establish common use

Application of the Doctrine

Two-Step Analysis

Courts typically apply a two-step analysis:

1. Determine if the weapon is in common use
   • Look at ownership statistics
   • Consider typical lawful purposes
   • Evaluate whether law-abiding citizens commonly possess it
2. If not in common use, determine if it's "dangerous and unusual"
   • Unusually dangerous beyond typical weapons
   • Not typically possessed for lawful purposes
   • May be subject to prohibition

Burden of Proof

Under the Bruen framework, once a plaintiff shows that a weapon is a bearable arm covered by the Second Amendment's text, the government bears the burden of proving either:

• The weapon is not in common use, OR
• A historical tradition supports regulating such weapons

Protected Weapons

Clearly Protected Categories

Supreme Court precedent and lower court decisions have recognized these weapons as clearly in common use:

Other Protected Arms

• Shotguns: Traditional sporting and self-defense weapons
• Standard Capacity Magazines: Magazines holding 10-30 rounds (circuit split)
• Tasers/Stun Guns: Protected per Caetano v. Massachusetts
• Ammunition: Necessary for firearm function

Unprotected Weapons

Dangerous and Unusual Weapons

Heller recognized that "dangerous and unusual weapons" that are not in common use may be prohibited:

• Machine Guns: Post-1986 machine guns (circuit consensus)
• Short-Barreled Rifles/Shotguns: NFA weapons (some debate)
• Destructive Devices: Grenades, bombs, missiles
• Unusual Weapons: Weapons not typically possessed for lawful purposes

The Machine Gun Example

Federal courts have consistently held that machine guns are not protected because:

1. The 1986 ban prevented them from entering common use
2. They are unusually dangerous
3. Not typically possessed by law-abiding citizens

"[M]achine guns are not in common use for lawful purposes and therefore fall outside the Second Amendment's protection."

— Hollis v. Lynch, 827 F.3d 436, 449 (5th Cir. 2016)

The Numerical Threshold Question

How Many Is "Common"?

Courts have not established a precise numerical threshold for common use:

Relative vs. Absolute Numbers

Courts consider both:

• Absolute numbers: Total weapons in circulation
• Relative prevalence: Percentage of households/gun owners possessing them
• Growth trends: Whether ownership is increasing

Criticisms and Debates

The Circularity Problem

Critics argue the doctrine creates circular reasoning:

1. Government bans a weapon
2. Ban prevents weapon from becoming common
3. Lack of common use justifies the ban
4. Ban is upheld because weapon isn't common

This criticism is particularly relevant for weapons banned before they could achieve widespread adoption.

The Heller Dichotomy

Some scholars note tension in Heller between:

• Protecting arms "in common use at the time" (modern weapons)
• Allowing prohibitions with historical precedent (historical approach)

Technological Advancement

Questions arise about new technologies:

• How can new weapons achieve common use if immediately banned?
• Should functionality matter more than specific models?
• How to handle weapons with both civilian and military variants?

Future Implications

Pending Questions

Several questions remain unresolved:

1. Magazine Capacity: Are magazines holding 10+ rounds in common use?
2. "Assault Weapons": Will the Supreme Court resolve the circuit split?
3. Accessories: How does the doctrine apply to firearm accessories?
4. Smart Guns: Can mandates for new technology violate common use?

Potential Supreme Court Clarification

The Supreme Court may need to address:

• Precise definition of "common use"
• Numerical thresholds
• Application to new technologies
• Relationship to the Bruen test

Legislative Considerations

Legislators must consider whether proposed regulations target weapons that are:

• Already in common use
• Functionally similar to protected arms
• Subject to historical analogues for regulation