What is the purpose of the Writ of Quo Warranto?

Writ of Quo Warranto is directed against a person who has wrongfully usurped an office. The office must be a 'public office' or an office of public nature.

The Writ calls upon the person to show under what authority he holds the office. If the court decides that the person concerned is holding that office illegally, it may declare the office to be vacant.