Excessive bail shall not be required, nor excessive fines imposed, nor cruel and unusual punishments inflicted.
So reads the Eighth Amendment to the United States Constitution. Please note that the Founders did not define the meaning, nor give examples, of the adjectives "cruel and unusual." Interpretation of the Constitution (and these terms) rests with state and federal judges, and for a legal system to function, there is a tier of judicial opinion that must be followed. When it comes to interpretation of a federal law (The Constitution), it would seem that federal courts override state courts.
Alabama has decided that this is not the case. The Supreme Court of Alabama has ruled that the decision of a US Federal District Court finding Alabama's ban of same-sex marriage unconstitutional was, in itself, unconstitutional, since the ruling defied Alabama's constitutional right to regulate its own marriage laws. Alabama's marriage law, then, trumps a federal courts's interpretation of the constitutionality of that law. At this point in time, the rulings of the Alabama Supreme Court stands, and probate judges are not issuing marriage licenses to same-sex couples.
Most felonies, including homicide, come under state regulation. Methods of punishment fall under a state court's jurisdiction as per the laws enacted by the state legislature.
Using the same argument, Alabama could rule that a hypothetical state law that includes punishment of a felony by water-boarding, sleep deprivation, weekly periods of starvation, or death by beheading, is also not subject to review by a federal district court, since said federal court has no judicial standing in Alabama's determination as to what constitutes "cruel and unusual" punishment under the Eighth Amendment. After all laws providing for punitive measures are left to the states.
The federal government is responsible to insure that Alabama comes into compliance with the rulings of federal courts
Denying same-sex couples the right to marry may not be unusual, but it can certainly be regarded as cruel!