"There is still a void there because the court intentionally did not make itself clear," Mr. McCalmon said. "It wasn't going to use this case to address privacy issues everywhere but someone will need to soon."

This issue--the impact of technology on employees and employers--is moving fast, Mr. McCalmon said.

"Here [Mr. Quon] was warned that his emails could be read, but he didn't think that applied to his texts," Mr. McCalmon said. "Now you can equate the two...on the public level."

The Supreme Court ruling overturned the U.S. Court of Appeals for the Ninth Circuit, which upheld an earlier ruling that Mr. Quon's rights were violated.

Justice Antonin Scalia said the court did not need to address whether its ruling applied in general to employees with employer-issued pagers because the city's search of Mr. Quon's texts did not violate the Fourth Amendment in the first place. Yet the court brought up the subject without stating its stance, something Justice Scalia found "indefensible."

"The-times-they-are-a-changin' is a feeble excuse for disregard of duty," he wrote. Justice Scalia said he worries lower courts will read into the decision as a "heavy-handed hint about how they should proceed."

Mr. McCalmon said government employees should get a private phone for private texts.