Royal assent is the final step required for a parliamentary bill to become law. Once a bill is presented to the Sovereign, he or she has the following formal options:
* grant royal assent, thereby making the bill an act of Parliament.
* delay the bill's assent through the use of reserve powers, thereby invoking a veto.
* refuse royal assent on the advice of his or her ministers.

The last bill that was refused assent was the Scottish Militia Bill