The objective of this study is to describe a new database containing detailed annual information on firearm-related laws in place in each of the 50 US states from 1991 to 2016 and to summarize key trends in firearm-related laws during this time period.
The aim of this database is to stimulate research that evaluates the efficacy of state firearm laws, including their impact on firearm-related homicide and suicide rates.
All laws were coded by the Principal Investigator in order to ensure consistency in the coding of legal provisions. First, the original coding was cross-validated by a second individual from a team of 20 graduate public health students. Two coders then evaluated each state's laws, with any discrepancies being resolved by mutual agreement.
Researchers compared the database with previous databases including law coding found in published books, monographs, and articles. Descrepancies were re-examined with the relevant statute, making a final decision based on close adherence to the codebook.
Firearm laws were coded using historical state statutes and session laws accessed from Thomson Reuters Westlaw and coded based on their year of implementation from 1991 to 2019.
134 state firearm law provisions in each of the 50 states in the United States of America for the period 1991 to 2019
Thomson Reuters Westlaw; Everytown for Gun Safety in collaboration with Legal Science, LLC; Bureau of Alcohol, Tobacco, Firearms, and Explosives' (ATF) "State Laws and Published Ordinances" (2000, 2006, and 2010-2011); Law Center to Prevent Gun Violence.
Each observation consists of a state-year observation. Each observation contains 134 dummy variables representing each firearm law provision. A 1 indicates the presence of that provision in that year. A 0 indicates the absence of that provision in that year. Laws are coded based on their date of implementation, not their date of enactment.
Laws that might be perceived as being intended to protect gun rights as opposed to public health (i.e., stand your ground laws, immunity statutes, and preemption laws) are coded such that a 0 represents the presence of such a law and a 1 represents the absence of such a law.
The classification by researchers attempted to account for the levels of gradation in some firearm laws by separately coding the operative terms of each law. The dichotomous coding of different provisions can easily be converted into a single scaled variable.