prerogative

Concise Oxford English Dictionary © 2008 Oxford University Press:
prerogative /prɪˈrɒgətɪv/

▶noun

• 1 a right or privilege exclusive to a particular individual or class.

• 2 (in UK law) the right of the sovereign, theoretically unrestricted but usually delegated to government or the judiciary.

▶adjective arising from or relating to the royal prerogative.

– origin ME: via OFr. from L. praerogativa ‘(the verdict of) the political division which was chosen to vote first in the assembly’, fem. of praerogativus ‘asked first’, from prae ‘before’ + rogare ‘ask’.