WASHINGTON - The Supreme Court is expected to decide soon, possibly today, whether to hear an appeal of a case in which employees won a constitutional right to privacy in their text messages, even when the messages were sexually explicit comments to coworkers.

Last year, the U.S. Court of Appeals for the Ninth Circuit ruled that the Fourth Amendment and a federal electronic-communications law protect the privacy rights of workers who send text messages on devices provided by an employer.

The appeals court ruled in favor of Police Sgt. Jeff Quon and three fellow officers in Ontario, Calif., who sued after the police chief read their messages.

"The Quon case is very important. It came down at a moment when there was virtually no protection for employee privacy," said Lewis Maltby, president of the National Workrights Institute in Princeton. "If it stands, it would mean employees for the first time could communicate at work with privacy."

The City of Ontario and its wireless-service provider appealed. Both were held liable for retrieving and reviewing the messages sent by Quon and his coworkers.

A Los Angeles lawyer who appealed on the city's behalf said the ruling sets a "troublesome" precedent for public agencies and private employers.

"The city had an explicit policy that employees had no expectation of privacy" when they were using its computers, cell phones, or pagers, said Kent L. Richland.

Quon and the other officers had signed a statement declaring that "users should have no expectation of privacy or confidentiality" when using computers or other devices given by the city.

But after text pagers were distributed to members of the SWAT team, the officers were told by a supervisor they could use them to send messages, so long as they paid out of their pocket for messages that exceeded a monthly limit of 25,000 characters.

It was understood that some of these messages would be unrelated to police work.

When Police Chief Lloyd Scharf learned some officers were regularly exceeding the limit, he asked for an audit.

An employee at Arch Wireless, the wireless service provider, sent transcripts of the text messages to the police chief. An internal-affairs report found that most of Quon's messages were personal, with sexually explicit comments to an officer who was said to be his girlfriend.

After Quon and the other officers learned their messages had been read, they sued. They lost before a federal judge in Los Angeles, but won before the Ninth Circuit.

In deciding for the officers, Judge Kim McLane Wardlaw said reading the text messages was an "unreasonable search" under the Fourth Amendment. Officials need clear evidence of wrongdoing before they listen in on private conversations, she said.

Second, she said the wireless provider violated the Electronic Communications Privacy Act of 1986 when it revealed the contents of the text messages.