Currently there exists no single metric that compares the lethality of weapons both within and between different time periods in a civilian context.  This lack of a single metric is a problem because public policy is made without distinguishing between different types of guns. Additionally, it is a problem for lawyers and judges who, after Bruen, must use analogs to apply historical regulations to modern ones. This lack of a common denominator for civilian lethality has led to a proliferation of dubious analogies in policy and legal arenas that a modern semiautomatic-rifle (like an AR-15) is “like” a revolutionary era musket because of its size, barrel length, popularity, or other superficial reasons.  

A common unit of lethality in the civilian context, such as has been constructed for the military, may help policymakers make apples-to-apples comparisons within and across time about the one functional aspect that all firearms share, in different degrees: lethality.

A working group of the Center for the Study of Guns & Society envisions a study inspired by the Theoretical and Operational Lethality indexes (TLI and OLI) developed by Col. Trevor Dupuy for the U.S. military in the 1960s. The Dupuy Institute head, Christopher Lawrence, presented a report on the TLI and OLI at the 2022 annual fall conference hosted by the Center at Wesleyan University. Subsequent discussions with Lawrence laid good groundwork for the present proposal. The TLI used a variety of carefully chosen criteria to calculate the number of people a shooter could theoretically kill in one hour with a given weapon. The Dupuy study found, for example, that a shooter with an 18th-century flintlock musket could kill 43 people, while a shooter with a 1903 Springfield rifle could kill 495. The lethality of modern, high-capacity assault rifles is higher still (in the 800–900 range, according to a recent conservative estimate from the Dupuy Institute). The Dupuy report also developed the OLI, which factors in conditions of war, using historical battlefield data (e.g. from the Napoleonic and American Civil War).

The value of a civilian arms lethality index for lawyers and policy makers is the subject of a 2022 law review article co-authored by legal scholar and Center advisory board member, Darrell A.H. Miller (Duke Law) and historian Jennifer Tucker (Founding Director, Center for the Study of Guns & Society, Wesleyan), titled “Common Use, Lineage, and Lethality,” published by UC Davis Law Review.