Here are the facts: the Livingston County (MI) jail has a very restrictive mail policy. Anything that's not legal mail has to be on a postcard. The jail administrator in charge of determining what constitutes legal mail thinks that only mail from a court and mail from an attorney to a current client constitutes legal mail. So the ACLU sent several letters to Livingston County inmates offering to help them challenge the county's policy. The letters were in enveloped marked "legal mail" and were signed by an attorney. But since Livingston County didn't consider them to be "legal mail," they were never delivered. The ACLU filed suit, seeking injunctive relief. The district court granted a preliminary injunction, and the defendants sought interlocutory review.
In its opinion, the court (Judges Moore, Siler, and Stranch comprised the panel, with Judge Moore writing) held that the jail's overly restrictive policy likely constituted violations of both the First and Fourteenth Amendments. The court's discussion at the bottom of page 10 of the opinion is particularly instructive: the court notes that legal services organizations like the ACLU must be able to send confidential communication prior to initiating legal action, and that both the inmate and the attorney have a strong interest in keeping communications confidential during the investigate stages of a legal matter. That should be particularly helpful for attorneys considering taking on postconviction or habeas matters on behalf of an inmate.