SAN FRANCISCO, CA — Text-messaging and email users “have a reasonable expectation of privacy” even in the workplace, according to a Wednesday ruling by the U.S. Court of Appeals for the Ninth Circuit.The unanimous, three-judge ruling both prohibits employers from accessing, without an employee’s permission, text messages transmitted by service providers (not over corporate networks) and limits employers’ access to email on in-house servers.

“The extent to which the Fourth Amendment provides protection for the contents of electronic communications in the Internet Age is an open question,” Judge Kim Wardlaw wrote in the opinion.

The question is less open now, and the Electronic Frontier Foundation is happy about that. In a posting at the organization’s website, it praised the judges’ decision, saying it demonstrates the Fourth Amendment “applies to your communications online just as strongly as it does to packages and letters.”

The ruling grew out of a 2002 lawsuit filed against the Ontario, CA, Police Department and Arch Communications by four police officers. In the complaint, the officers charged their employer and its communications subcontractor with infringement of their right to privacy after the department obtained transcripts of the officers’ pager messages while investigating whether the department-issued devices were being used solely for official business.

An attorney for the City of Ontario said the police department probably will appeal the ruling.