CHICAGO — In May of 2002, a 23-year-old man named Michael Brandon Shuler was sentenced in federal court to 15 years in prison for illegally possessing a gun — something that even the prosecutor acknowledged was a “rather benign act.”

Mr. Shuler’s lengthy sentence may seem cruel, but sadly it wasn’t unusual. It came courtesy of the Armed Career Criminal Act, a federal law that carries a mandatory minimum sentence of 15 years for people who possess a gun and have three prior convictions for certain crimes. These crimes include drug offenses and “violent” crimes, a category that encompasses a range of charges, such as breaking and entering, that may involve no actual physical violence.

The latter situation was the case with Mr. Shuler. At 18, having grown up in a poor Appalachian town in Virginia and struggled with mental health problems, he broke into several schools to steal prescriptions for pills to which he had become addicted. He was arrested and convicted on charges of larceny and breaking and entering. The sentencing judge described Mr. Shuler’s crimes as “nonviolent.” He served about a year in jail.

Then, when Mr. Shuler was 22, his mother died in a car accident, and he inherited from her a pistol and shotgun. After he picked them up, he visited someone whose home was raided (while Mr. Shuler was present) by members of the local Sheriff’s Department, looking for drugs. They happened upon Mr. Shuler’s guns, and several months later, Mr. Shuler was questioned by the Bureau of Alcohol, Tobacco, Firearms and Explosives. He was eventually arrested and charged with violating the Armed Career Criminal Act. Because his prior offenses counted as violent crimes under the law, the judge had no option but to sentence him to 15 years.

We are accustomed to hearing about exorbitant mandatory minimum sentencing for drug offenses, but similar sentencing for gun possession is less frequently mentioned, though its effects are often just as devastating, especially for poor people and people of color. In fact, a black person is nearly twice as likely to face a mandatory minimum carrying charge than a white person who is prosecuted for the same conduct.

When judges combine mandatory sentences for relatively minor, nonviolent charges, people convicted of gun possession offenses can receive prison terms lasting decades. In Texas in 2006, DeJarion Echols, a young black college student with no prior convictions, was sentenced to 20 years in federal prison: 10 years thanks to a mandatory minimum for possession of a small amount of crack cocaine (40 grams); and 10 more years thanks to a mandatory minimum for possession of a firearm in connection with a drug-trafficking charge. “This is one of those situations where I’d like to see a congressman sitting before me,” the sentencing judge said, in evident frustration.

Federal law is not unique in its use of minimum gun sentencing: Many states require mandatory sentences for illegal firearm possession and possession of a firearm during a felony. In New York, having an illegal firearm will get you at least three and a half years behind bars; a similar penalty was recently deemed “cruel and unusual punishment” when the Court of Appeal in Ontario, Canada, struck down three-year mandatory sentences for illegal gun possession as unconstitutional.

Mandatory minimum gun laws have historically been favored by gun control advocates and gun rights proponents alike. Supporters insist that mandatory minimums diminish violence via incapacitation (putting potential shooters in prison) and deterrence.

But there is no good evidence that mandatory minimum gun laws actually have this effect. A recent report issued by the Bluhm Legal Clinic of the Northwestern University Law School concluded that “decades of empirical evidence and evaluations of specific state experiences demonstrate that mandatory sentences will not reduce gun violence.” Studies of the impact of such laws in Florida, Massachusetts, Virginia and Michigan found no discernible effect on violent crime rates. In return for issuing these sentences, society reaps only the heavy burdens that come with lengthy incarceration, perhaps the least of which is higher costs to taxpayers.

Opposition to mandatory sentencing for drug-related offenses is steadily growing. Now we must widen our criticism to encompass mandatory minimums for firearms. These laws are not reducing violence. They’re simply fueling a different kind of violence: the banishment and isolation of large numbers of people, especially people of color and poor people, tearing apart their lives, families and communities.