The U.S. Constitution’s bill of rights prohibits “cruel and unusual punishment”. I am asking about a catch: cruel and usual punishment. If a punishment were determined to be cruel but is commonplace would it be constitutional?
As a preliminary note, the mandate that “Excessive bail shall not be required, nor excessive fines imposed, nor cruel and unusual punishments inflicted” can be interpreted two ways, (a) prohibiting punishments which are cruel as well as those which are unusual, or (b) prohibiting just those which are both cruel and unusual. The courts have not interpreted this to have meaning (b), even though "cruel and unusual" is a fixed phrase repeated in court rulings.
In various cases where the "cruel and unusual" clause is invoked, e.g. Solem v. Helm, 463 U.S. 277, Weems v. United States, 217 U.S. 349, Robinson v. California, 370 U.S. 660, Lockyer v. Andrade, 538 U.S. 63 the courts consistently analyze the punishment in terms of being jointly "cruel and unusual", and never consider the possibility that a punishment might be cruel but usual, or unusual but not cruel.
The prohibition derives from the pre-American "cruell and unusuall Punishments" provision of the English Declaration of Rights, analyzed in Harmelin v. Michigan, 501 U.S. 957, which provides "[t]hat excessive Baile ought not to be required nor excessive Fines imposed nor cruell and unusuall Punishments inflicted". The court observes that cruel punishments can indeed be quite common, for example
But the vicious punishments for treason decreed in the Bloody Assizes (drawing and quartering, burning of women felons, beheading, disembowling, etc.) were common in that period -- indeed, they were specifically authorized by law, and remained so for many years afterwards.
The court concludes from its historical analysis that "unusual(l)" in the context of English common law really means "illegal", i.e.
"contrary to Law and ancient practice," without "Precedents" or "express Law to warrant," "unusual," "illegal," or imposed by "Pretence to a discretionary Power."
The U.S. case law doesn't have a clear black and white resolution of that issue, which plays out differently in particular fact patterns on mostly a categorical basis under existing, much criticized case law. Pretty much, 8th Amendment jurisprudence in the U.S. can be summed up as follows:
Many kinds of corporal punishment short of the death penalty are prohibited as punishment even if similar uses of physical force were legal to secure someone's arrest or for the purposes of maintaining order in a prison or jail.
The death penalty in various circumstances (e.g. rape of an adult woman, ordinary crimes not resulting in death or a strong presumption that a death has occurred, offenders under the age of eighteen when the crime is committed) is barred by the 8th Amendment.
Life in prison without possibility of parole for a person who was a minor when the crime was committed violates the 8th Amendment.
Very long sentences for very minor crimes for first offenders (e.g. life in prison for writing a bad check) are prohibited.
There is almost no limitation on long sentences in prison sentences for adult recidivist felons. The 8th Amendment as interpreted by existing case law allows a life without possibility of parole sentence for non-violent shoplifting of about $100 by a person with multiple prior felony convictions, for example.
The circumstances under which long solitary confinement is prohibited by the 8th Amendment an unresolved issue upon which there is a split of legal authority that has not been definitively resolved.
Imprisonment of someone for failure to pay a debt that they are unable to pay, is prohibited, although incarceration for willful failure to pay a debt that someone is able to pay, or for failing to attend a hearing or respond to duly issued interrogatories issued to a debtor in the debt collection process, is not prohibited.
The reasoning behind these determinations is not entirely consistent between particular sub-types of punishments prohibited by the 8th Amendment.
There are also multiple statutory and non-8th Amendment grounds upon which sentences can be contested.
For example, a sentence in excess of the maximum punishment authorized by statute for the crime of conviction by a jury, in a case where there is a right to a jury trial, is invalid, but not under the 8th Amendment.
Similarly, disparate statutory sentencing rules for statutory rape based upon gender have been struck down on 14th Amendment equal protection grounds.
As a third example, a sentence (e.g. a death penalty determination) may be struck down because adequate due process was not provided when it was imposed or state law was violated when it was imposed.
It also bears mentioning that 8th Amendment issues are evaluated at the time they are litigated based upon "evolving standards of decency" rather than under the standards of what would have constituted cruel and unusual punishment in 1791 when the 8th Amendment was adopted. A precedent from 1810, for example, under the 8th Amendment, is not necessarily binding in 2020.