In the latest sign of the disconnect between the legal system and an increasingly sexualized adolescent cyberculture, two 13-year-old Pennsylvania girls are threatened with child pornography charges for sending seminude photos of themselves via cellphone to their friends.

A third girl, 16, who sent a picture of herself wrapped in a towel at her waist after a shower, may also face charges.

“Sexting” or “sexing,” the practice of sending nude or seminude pictures via cellphone or posting them online, is on the rise. A recent study by the National Campaign to Prevent Teen Pregnancy found that one in five teenagers admitting to having posted or sent a nude or seminude picture of themselves. In another survey by wiredsafety.org, an Internet safety and educational nonprofit organization, 44 percent of teen boys said they have seen at least one naked picture of a female classmate.

Over the past year, as schools and parents in states from Ohio and New Jersey to Colorado and California have found out about the practice, prosecutors have also become involved, in some cases threatening felony charges against the teenagers.

The incidents have sparked a nascent national campaign to educate parents and change the laws.

“The laws are either too hot or too cold and we need to make sure we find one that is just right,” says Perry Aftab, an online safety and privacy expert who founded wiredsafety.org. “We are either charging kids under child pornography and sexual exploitation laws as if they were registered sex offenders – which they will be if they’re successfully prosecuted – or we’re giving them a slap on the wrist with harassment laws that were not intended to address this.”

The situation in Tunkhannock, Pa., illustrates the extent to which “sexting” has become part of adolescent culture and the dilemma that it presents to parents, teachers, and law enforcement officials.

Last October, officials at the Tunkhannock Area High School, which is in a rural community north of Scranton, confiscated several cellphones from students and discovered pictures of scantily clad or seminude female students on them. Parents were alerted, and so were the police. In November, the local district attorney sent a letter to parents stating they’d discovered a “disturbing trend” and that they were investigating “several juveniles for possessing nude or seminude photos of young girls.” The letter went on to warn parents of the legal consequences as well as the fact that the teens appeared to be unaware of them.

“One young lady, when questioned about her photo being on a cell phone, called this ‘flirting’,” the letter stated.

With an estimated 20 teens involved, district attorney George Skumanick decided to try what he calls “a progressive” approach to the problem. In February, he sent another letter to the teens’ parents saying that if the students agreed to be placed on probation, submit to random drug testing and take part in a five-week counseling program, he would not press felony charges.

“It was mainly a crime of foolishness and naiveté, so we developed a program,” says Mr. Skumanick.

Most of the students agreed to take the classes. But the parents of three of the students felt the district attorney had gone too far in threatening felony charges. They went to the American Civil Liberties Union (ACLU), which brought suit against the district attorney charging that he was “standing child pornography laws on their heads.”

Sending seminude pictures is “stupid, careless, naive, poor judgment – all of the things that teenagers are and it could have really bad consequences for the future. But is it criminal and is it child pornography?” asks Witold Walczak, legal director of the ACLU in Pennsylvania. “These photos are not child pornography by production or by content – the Supreme Court has repeatedly said the definition of pornography is much narrower than just nudity.”

The district attorney’s decision to threaten child pornography charges against kids wearing underwear or in a bathing suit, Mr. Walczak says, is “a complete abuse his authority.”

District attorney Skumanick disagrees. “We tried to do what we thought was the progressive and the right thing by not charging them – by giving them the ability to avoid any record whatsoever,” he says.

The ACLU’s stance on the issue, Skumanick contends, would make it possible for anyone to bypass state laws and go directly to federal court charging their civil rights were violated before they were even charged with a crime. “That could cripple the criminal justice system,” he argues.

A judge is currently reviewing the ACLU’s request for a temporary restraining order against the district attorney. A ruling is expected this week.

For cyber-safety and teen advocates trying to raise awareness of the issue, the complexities of the Tunkhannock case simply reinforce the need to educate parents about the extent of “sexting” and students about the potentially severe consequences of the practice.

“Parents do not realize how widespread sexing is or how quickly the number of cases are rising,” says Casi L., an 11th grader at Ursuline School in New Rochelle, N.Y., who’s been working on cyber-safety issues since the 8th grade.

“A lot of kids feel anonymous online so they feel more comfortable doing inappropriate things because they think they won’t be linked back to them.”

The survey by the National Campaign to Prevent Teen Pregnancy also found that one in three young adults aged 20 to 26 had also sent nude or seminude pictures by phone or posted them online. Bill Albert, a spokesman for the National Campaign, says he believes those numbers are low because they were self-reported.

“We specifically put this question so that it was not open to interpretation,” says Mr. Albert. “Nude is nude, and seminude is seminude. If a person is in their bra, we wouldn’t classify that as seminude – if one of the 13-year-olds involved in this [Pennsylvania] case took our survey she’d check ‘no’ and appropriately so.”

The survey also found that young people have mixed feelings about the practice. The vast majority – 66 percent of teen girls and 60 percent of teen boys – say they thought of sexting as “fun or flirtatious,” but more than 70 percent also recognized it could have serious, long-term consequences in terms of their careers or social standing.

“But legal consequences were very low on their list of concerns,” says Albert.