The Eighth Amendment of the US Constitution prohibits the application of 'Cruel and Unusual Punishment' on a human being. There are four primary dimensions to decide if a given punishment is considered 'cruel' and 'unusual':
- frequency of its occurrence in society
- acceptance in society
- severity of punishment (does it fit the crime)
- if the punishment is arbitrary
There has often been debate on what constitutes 'cruel and unusual' punishment. The above guiding dimensions help one decide whether a specific punishment can be termed 'cruel and unusual'. Some clear examples of such punishments are Crucifixion, disembowelment, execution by burning, impalement, sawing, use of the breaking wheel, etc. Not only are these examples not acceptable in contemporary society, they are also arbitrary and some question their severity (with reference to the crimes committed). The debate on the death penalty and how it is carried out (electric chair, lethal injection, hanging, etc.) still continues. In somewhat recent times, "enhanced interrogation techniques" used on prisoners in Guantanamo Bay have been termed as NOT cruel or unusual. Yet excessive physical force constitutes cruel and unusual punishment even if there is no serious injury.
Also note that 'cruel and unusual' is a relative term and its interpretation varies from country to country (for example, stoning to death and amputation are still practiced in Saudi Arabia) and from peace time to war time (torture of suspected anti-nationalists or terrorists). Therefore, even though the Eighth amendment prohibits 'cruel and unusual punishment', an exact definition and an all-inclusive list of such punishments is not available and is open to interpretation by the court.