Our expert survey asked dozens of social scientists, lawyers and public health officials how effective each of 29 policies would be in reducing firearm homicide deaths, regardless of their political feasibility or cost. Policies deemed both effective and popular appear in the upper-right corner of the matrix. Less popular, less effective measures fall lower down and to the left.

The two policies ranked most effective were those requiring all sellers to run background checks on anyone who buys a gun, and barring gun sales to people convicted of violent misdemeanors, including domestic assaults. The experts were more skeptical of other much-debated proposals, including a national gun registry and an assault weapons ban. The idea of requiring states to honor out-of-state concealed weapon permits was ranked low.