prerogative (pri-rog-<<schwa>>-tiv), n. An exclusive right, power, privilege, or immunity, usu. acquired by virtue of office. — prerogative,adj.

prerogative of mercy. The limited discretionary power of a supreme authority, such as a state governor, national president, or sovereign, to commute a death sentence, change the method of execution, or issue a pardon, esp. for a person convicted of a capital crime.

[Blacks Law 8th]