VIOLENT MISDEMEANORS Federal law prohibits felons from buying and possessing firearms; it also bars people convicted of a misdemeanor crime of domestic violence. But it permits gun purchase and ownership by people convicted of other violent misdemeanors, defined variously under state laws, including assault and battery, brandishing a weapon or making open, credible threats of violence. Many people convicted of violent misdemeanors were originally charged with felonies but then convicted of lesser charges because of plea bargains. And research shows that people who have been convicted of any misdemeanors and who then legally buy a handgun are more likely to commit crimes after that gun purchase than buyers with no prior convictions.

California provides a case study. It changed its law in 1991 to prohibit individuals convicted of violent misdemeanors from buying guns for 10 years after the conviction. Before that, a study showed that gun buyers with even a single prior misdemeanor conviction were nearly five times as likely as those with no criminal history to be arrested for gun-related or other violent crimes. After the law was enacted, a significant decrease in arrests was attributed to the denial of gun sales to people with misdemeanor records.

ALCOHOL ABUSE Federal law prohibits the purchase and possession of guns by anyone who is “an unlawful user of or addicted to any controlled substance.” But the statute ignores alcohol abuse. That is also a mistake. The evidence linking alcohol abuse and gun-related violence is compelling. One study found that subjects who had ever been in trouble at work for drinking or were ever hospitalized for alcohol abuse were at increased risk of committing homicide and suicide.

Other studies also suggest that alcohol abuse is a factor in the association between gun ownership and the criminal justice system. The difficulty in policing alcohol abuse for purposes of gun control is that there is no precise definition of abuse. Pennsylvania, however, provides a useful example. It bars gun purchases by those who have been convicted of three or more drunken driving offenses within a five-year period. That criterion identifies drinkers with demonstrated tendencies toward recklessness and lawbreaking.

President Obama has instructed the Justice Department to review the federal prohibitions on gun ownership and to make legislative and executive recommendations “to ensure dangerous people aren’t slipping through the cracks.” The answers are already out there.