In a case that could have far-reaching impact on private employers, the Supreme Court is reviewing a decision that granted privacy protection to text messages sent over a third-party communication system paid for by the employer, in this case, the city of Ontario, Calif., police department.

The Ninth Circuit Court of Appeal, in Quon v. Arch Wireless,  ruled that the plaintiff’s privacy rights had been violated when the police department obtained copies of his sexually explicit text messages from Arch Wireless. The court based its decision in large part on a police department representative’s testimony that the department told Quon it would not review any text messages if the user paid all overage charges.

On the issue of whether Arch had the right to release the messages, the court held that it clearly did not since doing so requires the permission of either sender or receiver. The Supreme Court let that part of the ruling stand, but now will weigh in on whether employees are entitled to an expectation of privacy while using employer-paid, third-party communication services.

It is well established that e-mails sent, serviced and stored on a company’s own system are subject to review by the employer, but the issue in Quon regards wireless devices relying on third-party systems. It remains to be seen if–and how far–the Supreme Court is willing to extend privacy protection to employees.