A trial is slated to start Tuesday in a federal court in Harrisburg over the way the state prison system delivers legal mail to prisoners.
The Department of Corrections policy was changed over fears drugs could get in, but the American Civil Liberties Union and three other prisoner-advocacy groups say it's infringing on inmates' rights.
The problem started late last summer.
In the span of a few weeks, dozens of guards and other staff in multiple state prisons started reporting symptoms the state said were consistent with accidental drug exposure.
The whole system was locked down. When the Corrections Department finally got things back to normal, new security measures were added.
One concerns legal mail. Instead of directly giving inmates letters from their lawyers, they're now photocopied in front of the recipients, and the prison temporarily retains the original.
The department maintains the retained letters are kept secure, and the practice is necessary to make sure drugs don't get in.
But the ACLU argues they can't be sure the letters aren't tampered with. They're suing on First Amendment grounds, along with the Pennsylvania Institutional Law Project, Abolitionist Law Center, and Amistad Law Project.
The trial is expected to last at least through this week.