In January, Adam Liston made a serious mistake. Liston, 18, a senior at Davis, Calif. High School, dropped off a few friends at school on his way to the gun range with a new shotgun in his gun rack. Someone reported seeing the gun, and the next day, the vice principal asked to search Liston's Ford F-250 truck. Liston readily agreed.

Six police cars arrived and officers swarmed the truck. As they searched, his heart sank. He realized he had forgotten to remove the shotgun, unloaded and still in its original box, from his truck after target shooting. Liston broke down in tears as officers confiscated the gun and arrested him. He was handcuffed and taken to the Yolo County Jail.

Police charged Liston with two felony violations of California Penal Code § 626.9, possessing a firearm within 1,000 feet of a school -- one for when he dropped off his friends, the other for when he returned the next day. He was released on $25,000 bail. In February, the school board voted 3-1 to expel him from Davis High.

The Sacramento Bee pointed out that Liston "had been a model citizen since the first grade" and printed several letters expressing the community's outrage. Liston "had never been a discipline problem in school and … never had a run-in with the law," the paper stated. He maintained good grades and already had college plans. His mother was president of the PTA.

No matter. Administrators, police, prosecutors and lawmakers used mindless "zero tolerance" policies to throw the book at him.

The American Bar Association says the modern zero-tolerance-for-children movement is a response to the school shootings of the 1990s. No one doubts the good intentions of those who pushed these policies; it's the enforcement that has raised concern. And Liston is far from the only victim of this noxious overcriminalization, although he may be one of its older victims:

• In New Jersey, Hamadi Alston, 8, found an L-shaped piece of paper in a schoolbook. He used it as many 8-year-olds would -- in a game of "cops and robbers" at the next recess, after which he was taken to the school office, interrogated to tears, then turned over to police for "threatening to kill other students" for saying "pow pow" during the playground game. He spent five hours in police custody and had to make two court appearances before charges were dropped.
• In Alabama, Austin Crittenden, 9, was suspended for "possession of a weapon -- firearm replica," when he brought a tiny plastic G.I. Joe handgun to his elementary school. The third-grader's principal "had to tape the gun to a piece of paper to keep from losing it," Austin's grandmother reported.
• In Georgia, a 5-year-old kindergarten student was suspended for bringing a plastic gun the size of a quarter to school. The principal backed down when a local TV station inquired about the suspension.
• In Spokane, Wash., an 8-year-old was suspended for having two tiny plastic G.I. Joe guns at school.

At another Alabama school, two boys were suspended for playing with toy guns that one had brought in for a school project.

And those are just the school punishments. A 9-year-old in Martin County, Fla., was arrested for aggravated assault and disrupting a school function for playing with his toy gun as he left school at the end of the day. A 10-year-old in Alabaster, Ala., was arrested for supposedly engaging in threatening behavior with a toy gun.

A 12-year-old boy in Louisiana with hyperactivity disorder was arrested for making a terrorist threat after he told students ahead of him in the lunch line to leave some potatoes, or "I'm going to get you." He spent two weeks in jail awaiting a hearing.

Zero-tolerance policies mock the legacy of Anglo-American jurisprudence. As Roscoe Pound, a preeminent legal scholar of the early 20th century, explained, "Criminal law is based upon a theory of punishing the vicious will. It postulates a free agent confronted with a choice between doing right and doing wrong and choosing freely to do wrong."

Does anyone believe these children chose freely to do wrong? Perhaps it's time we penalize overzealous adults who don't check their predilections for overcriminalization at the door of common sense.

Paul Rosenzweig is senior legal research fellow in the Center for Legal and Judicial Studies at The Heritage Foundation (heritage.org) and adjunct professor of law at George Mason University. Trent England is a legal policy analyst in the Center. Read more about these issues at overcriminalized.com.