The Supreme Court declared that it would assume that state courts relied on federal law unless the courts clearly demonstrated otherwise.
By a 6-3 vote, the Supreme Court attempted to unravel the perplexing question of how to interpret the “independent and adequate state grounds” issue. The case sprang from a Michigan supreme court decision about automobile searches. The ambiguity concerning just what constitutional provisions were involved in the lower court’s decision led the Court to declare that it would regard state decisions as being based on federal law in most cases. In her opinion for the Court, Justice Sandra Day O’Connor
Erie Railroad Co. v. Tompkins
Gelpcke v. Dubuque
Independent and adequate state grounds doctrine
Swift v. Tyson