It is well established that federal courts generally lack jurisdiction in criminal cases to review errors of state law. This is true of direct review by the United States Supreme Court and when criminal defendants seek habeas review. This article examines federal court treatment of state law errors in criminal cases. It concludes that the phrase “mere error of state law” has usually been the end point of federal analysis, and that this is in essence judicial abdication. Defendants have a right to a meaningful appeal, and just as counsel cannot act ineffectively to deny a fair appeal the Due Process Clause should act as a check on appellate courts which act in an irrational, fundamentally unfair or arbitrary and capricious manner. The article attempts to take into account jurisdictional limitations and notions of comity in providing a framework for identifying those rare instances when a state appellate court should be found to have violated a defendant’s due process rights.