A writ of prohibition restrains a body exercising public power from exceeding its powers or usurping jurisdiction which it does not have. That is, it prohibits the decision maker and those relying on the decision from doing something which they are about to do, or from continuing a course of action already commenced, such as taking any further step in proceedings.
The basis upon which the writ is commonly issued is:
Want, or excess, of jurisdiction.
Breach of natural justice.
