Excessive punishments.

Excessive fines, cruel and unusual punishment, attainder, forfeiture of estate, indefinite imprisonment, and unreasonable detention of witnesses are forbidden. The death penalty is an authorized punishment for capital crimes designated by the legislature. The prohibition against cruel or unusual punishment, and the prohibition against cruel and unusual punishment, shall be construed in conformity with decisions of the United States Supreme Court which interpret the prohibition against cruel and unusual punishment provided in the Eighth Amendment to the United States Constitution. Any method of execution shall be allowed, unless prohibited by the United States Constitution. Methods of execution may be designated by the legislature, and a change in any method of execution may be applied retroactively. A sentence of death shall not be reduced on the basis that a method of execution is invalid. In any case in which an execution method is declared invalid, the death sentence shall remain in force until the sentence can be lawfully executed by any valid method. This section shall apply retroactively.