If you want to understand all that is wrong with America's criminal justice system, take a look at the nightmare experienced by Edward Young.
Mr. Young, now 43, was convicted of several burglaries as a young man but then resolved that he would turn his life around. Released from prison in 1996, he married, worked six days a week and raised four children in Hixson, Tenn.
Then a neighbor died, and his widow, Neva Mumpower, asked Mr. Young to help sell her husband's belongings. He later found, mixed in among them, seven shotgun shells, and he put them aside so that his children wouldn't find them.
"He was trying to help me out," Ms. Mumpower told me. "My husband was a pack rat, and I was trying to clear things out."
Then Mr. Young became a suspect in burglaries at storage facilities and vehicles in the area, and the police searched his home and found the forgotten shotgun shells as well as some stolen goods. The U.S. attorney in Chattanooga prosecuted Mr. Young under a federal law that bars ex-felons from possessing guns or ammunition. In this case, under the Armed Career Criminal Act, that meant a 15-year minimum sentence.
The U.S. attorney, William Killian, went after Mr. Young -- even though none of Young's past crimes involved a gun, even though Mr. Young had no shotgun or other weapon to go with the seven shells, and even though, by all accounts, he had no idea that he was violating the law when he helped Ms. Mumpower sell her husband's belongings.
In May, a federal judge, acknowledging that the case was Dickensian but saying that he had no leeway under the law, sentenced Mr. Young to serve a minimum of 15 years in federal prison. It didn't matter that the local authorities eventually dismissed the burglary charges.
So the federal government, at a time when it is cutting education spending, is preparing to spend $415,000 during the next 15 years to imprison a man for innocently possessing seven shotgun shells while trying to help a widow in the neighborhood. And, under the law, there is no early release: Mr. Young will spend the full 15 years in prison.
This case captures what is wrong with our "justice" system: We have invested in mass incarceration in ways that are crushingly expensive, break up families and are often simply cruel. With less than 5 percent of the world's population, the United States has almost one-quarter of the world's prisoners.
This hasn't always been the case, but it is the result of policies such as mandatory minimum sentences since the 1970s.
In 1978, the United States had 307,000 inmates in state and federal prisons. That soared to a peak of more than 1.6 million in 2009. Since then, the number of inmates has declined for three consecutive years to 1.57 million in 2012. The number of juveniles detained has also begun to drop since peaking in 2000, although the United States still detains children at a rate five times that of the next highest country.
In short, there's some hope that this U.S. experiment in mass incarceration has been recognized as a failure and will be gradually unwound. Among the leaders in moving away from the old policies are blue states and red states alike, including New York and Texas. But America still has twice as many prisoners today as under President Ronald Reagan.
Almost everyone seems to acknowledge that locking up vast numbers of nonviolent offenders is a waste of money. California devotes $179,400 to keep a juvenile in detention for a year, and spends less than $10,000 per student in its schools.
Granted, mass incarceration may have been one factor in reduced crime in the last couple of decades; there's mixed evidence. But, if so, the economic and social cost has been enormous -- including the breakup of families and the increased risk that children of those families will become criminals a generation later.
There's also contrary evidence that incarceration, especially of young people, doesn't work well in preventing crime, especially for young people. One careful study of 35,000 young offenders by Anna Aizer and Joseph J. Doyle Jr. reached the startling conclusion that jailing juveniles leads them to be more likely to commit crimes as adults.
Mass incarceration has been particularly devastating for blacks and members of other minority groups, as well as for the poor generally. In this case, Edward Young is white.
Conservatives often argue that there is a link between family breakdown and cycles of poverty. They're right: Boys are more likely to get into trouble without a dad at home, and we have a major problem with the irresponsibility of young men who conceive babies but don't raise them.
We also have a serious problem with the irresponsibility of mass incarceration. When almost 1 percent of Americans are imprisoned (and a far higher percentage of men of color in low-income neighborhoods), our criminal justice system becomes a cause of family breakdown and contributes to the delinquency of a generation of children.
Mr. Young is particularly close to his children, ages 6 to 16. After back problems and rheumatoid arthritis left him disabled, he was a stay-at-home dad while his wife worked in a doctor's office. When the judge announced the sentence, the children all burst into tears.
"I can't believe my kids lose their daddy for the next 15 years," his wife, Stacy, told me. "He never tried to get a firearm in the 16 years I was with him. It's crazy. He's getting a longer sentence than people who've killed or raped."
I asked Mr. Killian, the U.S. attorney, why on earth he would want to send a man to prison for 15 years for innocently possessing seven shotgun shells. "The case raised serious public safety concerns," Mr. Killian said.
The classic caricature of justice run amok is Inspector Javert in Victor Hugo's novel "Les Misérables," pursuing Jean Valjean for stealing bread for hungry children. In that case, Valjean knew that he was breaking the law; Edward Young had no idea.
Some day, Americans will look back and wonder at how we as a society could be much more willing to invest in prisons than in schools. They will be astonished that we sent a man to federal prison for 15 years for trying to help a widow.
Nicholas D. Kristof is a syndicated columnist for The New York Times.