WASHINGTON – Three high school students in Fairfax County, Virginia, made cellphone videos of drunken sex acts with fellow teens and shared them among themselves. Now they are going on trial, facing a charge usually reserved for adult predators: child pornography.

The case is one of a number in Virginia where teens caught “sexting” have been charged with a felony that can carry a sentence of 20 years in prison and could require registry as a sex offender.

In Virginia, Maryland and many other states, the law has not caught up with the combustible mix of teens, technology and sex that has made sexting an issue. Prosecutors must rely on a patchwork of laws that were created before the rise of smartphones to handle such cases.

Some parents and rights groups are calling for a new law that would distinguish sexting from child pornography, create lesser punishments and focus on educating teenagers instead of punishing them. But they also acknowledge that young victims can be devastated when embarrassing photos or videos are spread among their peers.

A mother whose 15-year-old son was charged with 12 counts of child pornography for sexting in Franklin County, Virginia, called the experience a nightmare. She said her son, who has Asperger’s syndrome, was naive when he sent out a topless photo of a classmate.

“It was probably the worst point of our life,” the woman said. “My son was in a severe depression. He is thinking his life was at an end. He could be labeled as a sex offender.”

Fairfax County Commonwealth Attorney Ray Morrogh said prosecutors across the state are grappling with how to handle sexting cases. He said that no one wants to slap a teen with a felony sex charge but that those concerns have to be weighed against the impact on a victim when an image or video goes public.

Parents of two teens in Ohio and Florida say their daughters committed suicide after they were ridiculed over sexually explicit images of them that were forwarded to others. And sexted images and videos can be found by child pornographers, who trade them on the Internet.

“We try to resolve these cases wherever possible without going to the courts,” Morrogh said. “At the juvenile level, the goal is to rehabilitate the child.”

Most sexting cases in which teens are initially charged with child pornography are resolved outside of court, or with lesser charges that result in probation or community service.

Morrogh declined to discuss the Fairfax case, but authorities have said two 16-year-olds and a 15-year-old from West Springfield High School were charged with possession and distribution of child pornography in January after they filmed themselves engaging in sex acts with at least six teenage girls. Their trial was set to open Thursday.

A source with the Fairfax school system said the videos were filmed surreptitiously.

Rodney Leffler, an attorney for one of the boys, has said that all of the sex acts were consensual and that the 10 videos at the heart of the case were filmed at parties at the teenagers’ homes, beginning in December 2011. He said that all of the girls eventually learned they were being filmed and that the boys shared the videos among themselves but did not distribute them widely. It is not clear whether the videos were texted, emailed or disseminated by other means.

The Franklin mother said that in her son’s case, a classmate borrowed his phone, went into a high school bathroom and took a topless photo of herself. She said the girl did not have a phone and wanted to send the photo to two other students.

When the boy got the phone back, he discovered the topless picture and forwarded it to friends. The boy, the girl and other students who received the photo were arrested under Virginia’s child pornography statute in 2010.

The mother said her son eventually pleaded no contest to the 12 charges of distribution of child pornography — one for each time he forwarded the photo. He was given probation for a year and required to do 60 days of community service. The charge has since been wiped from his record.

In Maryland, Montgomery County State Attorney John McCarthy said he has yet to prosecute a sexting case, but added he sees them as “opportunities for education and intervention.” Nevertheless, he said the state might benefit from a specific sexting statute to address situations where explicit photos are shared willingly between underage teens of around the same age.

“The existing laws are inadequate to address sexting,” McCarthy said.

There has been little movement to create a sexting law in Maryland, but the Virginia State Crime Commission explored the idea in 2009. The commission ultimately did not recommend any legislation. A bill that would make sexting a misdemeanor also went nowhere in 2010.

The sticking point: Legislators say they worry that such a law could unintentionally open a loophole that might be exploited by pedophiles.

“Every time we try to write a carve out for this specific situation, we just give the true sex predator a road map on how to commit a crime,” said state Delegate David Albo, a Republican. “You cannot make a mistake when you are drafting this type of bill. The stakes are too high.”

In addition, the circumstances of these cases vary widely, ranging from a girl willingly texting a racy photo of herself to a boyfriend who does not share it to teens secretly recording sex acts and maliciously spreading the videos.

SMS messages remain the most popular way to send messages worldwide, 20 years after their invention, despite competition from email and social networking messaging services.

Text messaging has also allowed criminals to communicate more freely, but the police have been catching up with the technology. Now police often use silent messages, or “stealth SMS,” which do not show up on a phone’s display but allow data to be created that help police locate or track a person.

Such tactics were used by British investigators in the hunt for Soham child killer Ian Huntley, who was convicted in 2003 of murdering two girls. In Germany in 2010, nearly half a million “silent SMS” were sent by the federal police, customs, and the secret service.

In America, at least 20 states have passed legislation on sexting since 2009, according to the National Conference of State Legislatures. States have generally moved to create more lenient punishments for sexting teens and to shield them from having to register as sex offenders.

A University of New Hampshire survey found that 7 percent of young people had received a nude or nearly nude image of others, while 1 percent said they had created sexually explicit images of themselves.

Jonathan Phillips, a lawyer and former Fairfax prosecutor, has handled sexting cases on both sides. He said there is room to find common ground on a sexting law in Virginia.

“If you look at some states, the age of the senders, the intent of the senders is considered. Having another statute doesn’t close out charging someone with child pornography. It’s better to have more of a spectrum of options,” Phillips said.