485 U. S. 264
March 21, 1988
A bunch of Native American activists decided to occupy the village of Wounded Knee, South Dakota in 1973. U.S. military personnel were eventually brought in to help control the activists, and things got ugly from there. The activists maintained that authorities had breached a federal law (the Posse Comitatus Act), which prohibited the U.S. military from assisting in domestic brawls. They also maintained that violating the Posse Comitatus Act was equivalent to violating the Fourth Amendment. Lower courts agreed, and the case then went to the Supreme Court.
Here’s where it gets weird: by statute, in order to even consider a case, six Supreme Court Justices must be available. After the Court took the case, Rehnquist, O’Connor, Scalia, and Kennedy all ended up recusing themselves, leaving only five other Justices. Thus, in a surreal per curiam paragraph, the Court said that it was impossible to decide the case, and let the lower ruling stand.