A north suburban high school is cracking down on campus drug sales by confiscating the cellphones of student suspects and using their text messages to identify others, an investigative technique that has raised questions among some legal experts and unnerved students who said they assumed texting to be private.

Stevenson High School spokesman Jim Conrey said the ongoing investigation, in which Lincolnshire police are also participating, has resulted in multiple suspensions, though he would not provide the number. He said examining student text messages was a legal and appropriate way to gather information about the alleged sales.

"That's perfectly within our rights within the school," he said. "If schools have credible evidence that cellphones are being used in some kind of trafficking … we have every right to take the phones."

As the lives of teens become increasingly intertwined with the technology they carry, investigators are finding revelations about alleged criminal behavior on cellphones, Facebook, Twitter and YouTube. In a twist, some parents complained that because the school wasn't saying much about what was happening, their primary source of information became those same social media sites.

And though Conrey said the privacy and legal issues were clear, some experts said courts and legislators are falling behind the galloping technologies.

Kimberly Small, assistant general counsel for the Illinois Association of School Boards, said theU.S. Supreme Courthas decided that school officials need only "reasonable suspicion" to search students' belongings, a lower standard than the "probable cause" that applies to police.

But she noted that a more recent federal law established that owners of electronic devices have a legitimate interest in the confidentiality of their messages. The law has yet to determine exactly how school administrators' search power intersects with that privacy concern, she said.

"It's such a gray area for everyone — students, parents, school officials, even law enforcement," she said.

Conrey offered few details of the origin or scope of Stevenson's investigation, saying that it started in December with one student suspected of being involved with drugs on campus, and went on to include others involved in the alleged sale of marijuana and other drugs.

Lincolnshire police were equally reticent, though Deputy Chief Greg Duffey said the department had obtained a court order to get text messaging records from cellphone carriers. Conrey said school officials were not involved in that aspect of the investigation.

Lincolnshire police Chief Peter Kinsey said no students have been arrested but that the state's attorney's office would decide any possible charges when the investigation is completed.

Those who attend the school described tense scenes on campus this week, with students called out of class to be confronted by police and administrators. Some students said they had seen a boy run from a school office and smash his phone before he was caught.

Junior Chris Geppert said many students were nervous, wondering if they would be unjustly accused.

"What if someone took your phone and texted you as a joke?" said Geppert, 16, of Riverwoods. "How can they do this with no hard facts?"

Conrey said school lawyers had approved the conduct of the investigation. But Matt Cohen, a Chicago attorney who represents students in disciplinary matters, said thorny legal issues can arise when administrators review students' text messages, particularly when the content of those messages could lead to criminal charges.

"It raises a real serious concern about the scope of the seizure, the scope of the intrusion on the private messages and whether there's any concrete basis for suspicion of the particular student," he said. "Kids say a lot of different things. They might have suggestive language (in their text messages) but it's not reflective of behavior."

Conrey said Wednesday morning that Stevenson officials, in accordance with their usual practice of keeping misconduct investigations private, had not informed parents about what was happening. By the afternoon, though, Superintendent Eric Twadell issued a statement that criticized "misinformation" in the media but provided no facts, saying only that the school took drug issues seriously.

The lack of information bothered Cathy Belmonte, whose son is a senior at the school.

"Parents and students alike are searching the Internet and Twitter feeds for information and spreading gossip and misinformation," she said. "With a school this large, it is dangerous to think that this could be contained and not result in gossip. Parents and students alike should be informed."

The suspensions spawned a Twitter hash tag — #SHSDrugBust2012 — and comments ranged from jokes to warnings about surveillance to expressions of disgust over drug use at the school. One student took to YouTube to issue an earnest plea about following the law.

"We go to a school that's one of the most highly regarded in the country, and we need to realize that we can't abuse that privilege," the student said. "Stevenson trusted (the accused students), and they broke that trust."

Conrey would not detail the punishments the school was handing out, but Stevenson's code of conduct calls for a five-day suspension for students caught with paraphernalia, a 10-day suspension and loss of various privileges for those caught with drugs, and a recommendation of expulsion for those accused of dealing.

The school board must agree to expel a student, and Conrey said no hearings have been set.

This is only the second year in which cellphones have been allowed on Stevenson's campus, and Conrey said there were no plans to change that policy. But sophomore Nick Moller, 16, who said several of his friends had been suspended, said the episode had thrown a chill into the school's student body.

"No one texts anymore," he said. "Some people don't bring their phones to school anymore. They're worried (administrators) can find one little thing from months ago and they'll get in trouble."

John Keilman is a Tribune reporter. Susan Berger is a freelance reporter. Freelance reporters Andrea L. Brown and Ruth Fuller contributed.