Francie Baldino, a mother of two from Royal Oak, Mich., can tell you the day she became an activist against America’s sex-offender laws. It was the day her teenage son went to prison—for falling in love with a teenage girl.

“Prison was unthinkable,” says Baldino. “He was just a dumb kid.”

Her son, Ken, was an 18-year-old senior in high school when he was arrested for having sex with his girlfriend, a 14-year-old freshman, in 2004. The age of consent in Michigan is 16. He got sentenced to a year in jail and three years of probation. After that, when the two teens resumed their relationship—violating his probation—he got five to 15 years.

His mother is part of a surprising rebellion that has now spread to all 50 states: parents fighting against sex-offender laws—the very laws designed to safeguard their children. These parents argue that the laws are imposing punishments on their high-school sons that are out of proportion to the crime.

Baldino’s son, for instance, spent more than six years behind bars and today must wear a GPS device the size of a box of butter. Sometimes, he says, it loses its signal and sets off an alarm. “That’s really helpful when I’m at work,” says the blue-eyed 26-year-old, who wears stud earrings and works at a door-and-window store.

No one keeps a tally of how many cases fall into this category nationwide. But there is one measure of the scale of the movement: there are now more than 50 organizations—at least one in every state—battling against prosecutions like these. Baldino’s group is Michigan Citizens for Justice, which she says includes more than 100 parents. Another group in Michigan, the Coalition for a Useful Registry, has around 150 parents as members, it says. Organizations in other states report similar numbers. One of the largest, Texas Voices, claims some 300 parents as members.

The cases they are fighting are highly complex, charged with emotion, and rarely black-and-white. The questions are profoundly difficult: Should the scales of justice be weighted in favor of the young? Is a sex crime somehow less terrible, if it involves teens? The judge in the Baldino case, Fred Mester, openly acknowledged the complexities. Referring to his own high-school days when handing down the prison sentence in 2005, he said, “Half my senior class … were dating freshman girls, and I suspect half of them would be in here today.”

Prosecutors say it’s simple: kids should obey the law, and parents need to keep their children under control. Paul Walton, a chief assistant prosecutor in Michigan, says Baldino’s son had only himself to blame: he was an adult, and he chose his own actions. “The court isn’t imposing restrictions because it’s fun—it’s the law,” Walton says. “You can disagree on the age of consent, but the law says that prior to that age, a person doesn’t have the ability to consent.”

Baldino is quick to say that she doesn’t advocate underage sex. And both she and her son admit he broke the law. He “did stupid things,” she says, including getting in a physical fight with his girlfriend’s father one evening in 2004—a fight that began the chain of events that led to the police being called, and his arrest for underage sex.

Baldino argues simply that the law should treat teenage lovers differently from pedophiles or violent sexual predators. “The punishment is too extreme for kids,” she says. “It’s a system that’s not working.”

ON A RECENT RAINY AFTERNOON, Francie Baldino steps into her kitchen and pulls out a favorite photo of her son as a toddler, dressed in a bee costume. Then she sits down at the table and describes the events that sent him to prison.

Baldino was a remarried mother of two when her son, Ken Thornsberry (who uses his father’s surname), met a girl named Emily Lester at a local Tower Records. The two teenagers were living with their fathers in the wake of divorce; both were struggling to find their footing at home and at school, says Baldino. They attended different high schools, but started spending all their free time together. Eventually, they slept together, although they certainly didn’t announce that to their parents.

Lester, now 22 and living in nearby Lake Orion, Mich., remembers the romance fondly. “I’ll never forget that day we met,” she says, recalling evenings spent wandering the county fair with her boyfriend, or listening to him play guitar in his high-school band. “I’ve never loved someone like Ken.”

Her father disapproved of the relationship, Lester says, and told the pair to split up. (Her father didn’t respond to attempts to contact him.)

The teens didn’t listen. “Ken was young,” says Baldino. “He was in love. He thought nothing bad could happen to him.” She admits that she wishes she had paid more attention, but in hindsight says she was focusing too much on running a graphic-design business.

One morning, Thornsberry drove to Lester’s house when he thought her father would be at work. His plan, he says: to pick up some belongings and drive his girlfriend to school. But her father saw Thornsberry outside the home and the two started arguing. Thornsberry kicked open the front door and hurled a sugar bowl at the TV. The father called the police. Thornsberry was arrested for home invasion.

When questioned by detectives, Thornsberry, then 18, admitted to sleeping with his 14-year-old girlfriend. On the advice of his attorney, he pleaded guilty to criminal sexual misconduct and was sentenced to a year in jail followed by three years’ probation, during which time he could not be around minors, including his girlfriend. He would also go on the sex-offender registry, which would list his home address and other personal information, for 25 years.

Baldino visited her son regularly in jail. “People say that when you’re 18, you’re an adult,” she says. “But he was just a kid.”

ACTIVISTS RAISE AN INTERESTING point: at what age does a person become an adult? The voting age is 18. The drinking age is 21. A person can join the military at the age of 17, with parental permission. The age of consent for sex varies by state, from age 16 to 18—so sex can be a crime in one state and not in another.

There are now more than 700,000 registered sex offenders nationwide, according to the Center for Missing and Exploited Children. Every state has its own registry; 34 states register youth offenders. There are no national statistics on the number of youths, because not every state keeps track. Individual state numbers vary: in Michigan, there are 1,341 registered youths. In Texas, there are 4,519; in Wisconsin, 1,687.

Sex-offender registries began for the most part in the '90s, after an 11-year-old boy named Jacob Wetterling was abducted in Minnesota. Congress created the Wetterling Act in 1994, requiring states to establish registries listing convicted sex offenders. Other federal acts followed, but the rules were broadly defined, so state laws varied widely.

In 2006, new federal legislation tried to bring some uniformity to the tangle of state laws by setting minimum standards across the states. However, only 15 states have implemented the terms to date. One big reason: cost. Budget-strapped states say they can’t afford the added administrative work.

KEN THORNSBERRY EMERGED from the county jail in 2005. He was 19 years old, and had a GED and a new job with his father’s contracting company. He stuck to his probation terms and didn’t see Emily Lester—for the first few months, anyway. Then, she contacted him, and he started secretly seeing her.

“He was acting like a dumb teenager,” Baldino says. One day, Lester’s father came home and found Thornsberry with his daughter. Back to jail he went.

In a court hearing, Lester pleaded her boyfriend’s case. “It’s just like, we were in love, and it’s just not fair,” she said, according to court documents. “It’s not like I was 12 or something.”

The prosecuting attorney, Kenneth Frazee, disagreed. “I think the victim you saw today is a person that’s very much in need of our protection,” he told the judge.

Judge Mester sympathized with the teens, pointing out that society encourages sex: “That’s all we read about ... these heroic celebrities from Hollywood telling us how we’re going to live our lives free and easy.” But the law, he said, is clear. He sentenced Thornsberry to five to 15 years.

“I made bad choices. I did stupid stuff,” Thornsberry says today, standing in his mother’s kitchen. He got out of prison this past August after more than six years. He was due to get out in five, but needed to take a sex-offender class first, and it was overbooked. He is now on parole for two years. He wears a GPS bracelet on his ankle and carries an accompanying black metal box that bleeps if he loses a signal or if he moves away from approved locales.

For the next two years, he cannot be around kids and must attend weekly sex-offender classes. He is not allowed to use a computer or cellphone camera. He’s 26 and has never used Facebook.

He demonstrates the heft of the GPS box, which weighs about a pound, by clipping it to his back pocket, causing his jeans to comically droop. He jokes about the time he left it on the counter at a gas station and the clerk thought it was a bomb.

Thornsberry laughs easily. His mother laughs with him, even when he mentions that when he was new in prison, an inmate offered him $60 to walk around the cell in his underpants—an offer he declined.

As her son speaks, Baldino flips through a stack of drawings he produced in prison: angry demons, a heart blown apart. Thornberry’s arms tell a story, too. When he went to prison, he had a couple of tattoos, he says—a star, a zipper around his wrist. He emerged with two fully covered arms, ringed with vines and bloodshot eyes. One of the inmates had rigged up a tattoo machine.

Baldino founded her reform group while her son was in prison.

SOME NEW “ROMEO AND JULIET” LAWS—inspired by parent-activists like Baldino—are designed to help high-school students in this predicament. The laws aim to reduce the penalties for sex with a minor, provided the couple’s age difference is minimal and other parameters are met. But some parents say the laws are still imperfect. For instance, the mandated age difference might be three years, but a boy might be three years and a month older than the girl.

Activist groups argue that teens who miss the parameters should go to a counseling or treatment center, not to jail. They also argue that teens shouldn’t be placed on the sex-offender registries.

Alison Parker, the U.S. program director for Human Rights Watch, argues the laws should change. “Common sense says that kids are different from adults,” she says. “Kids can grow and change. They are extremely unlikely to reoffend.” The recidivism rate among juveniles who commit sex offenses is 4 to 7 percent, she says, citing a study published in Sexual Abuse: A Journal of Research and Treatment. For adults, she notes, the recidivism rate is 13 percent, according to a study in the Journal of Consulting and Clinical Psychology.

Dena Teska, a mother in Sturgeon Bay, Wis., agrees. Last month, her son Christian was sentenced to nine months in jail. He was 18 when he was arrested, in 2010, for having a sexual relationship with his 15-year-old girlfriend. A fellow student had told a school guidance counselor about the relationship, and the counselor told the police. The age of consent in Wisconsin is 18.

He pleaded guilty to fourth-degree sexual assault and was sentenced to probation for two years, during which time he had to stay away from his girlfriend. He didn’t. Arrested again this past fall, he will serve his sentence in the county jail.

His mother admits he made mistakes but thinks jail is not the answer. “My son thinks he has found the love of his life,” she says. “He’s a teenager. They should put him in a treatment program, not a horrendously wicked place.”

Joan Korb, the assistant district attorney on the case, feels differently. She says Teska’s son is an adult, and that he was given “plenty of opportunities to follow the rules” while on probation. “When a judge orders you to do something, you do it,” she says, adding: “I wish parents would teach their kids respect for authority, the law, and other people.”

HIGH-SCHOOL SWEETHEARTS Ken Thornsberry and Emily Lester had a brief reunion this past August, in court. Thornsberry, newly out of prison, had a chance to petition the court to remove his name from the sex-offender registry, due to a new law spurred on by parent activists. In order to be freed from the registry, he needed to petition two judges. The first judge had ruled against him, so Lester was called upon to appear before the second judge.

“I was so nervous,” Lester says, describing the morning she got the call. “I hadn’t seen Ken in eight years.” She begins to cry. “He hugged me. It’s like we just picked up where we left off. I wasn’t nervous anymore. It was him.” The two are not allowed to contact each other for the next two years, as she is considered his victim.

“I’m not a victim,” she says. The term makes her angry. “I’m not a minor. He didn’t rape me.” She has moved on, and so has he. Both today are dating other people. But there are unresolved feelings, Lester says: “Our relationship was just cut off.”

Thornsberry is now off the sex-offender registry. But he remains a convicted felon for life, according to his attorney, Cheryl Carpenter. She has freed 20 youth offenders from the sex-offender registry in Michigan; she is among those who think the laws need to change. “The laws often don’t differentiate between a 50-year-old man molesting a 14-year-old girl, and two teenagers having sex,” she says.

Today, Thornsberry is launching his own landscaping business, and also applying at Oakland Community College for a business degree. His plan: to start a music venue where bands can play and artists can display their work.

“I’ve already lost so much time,” he says. “I’m 26. If that doesn’t give you the gas to get going, I don’t know what does."