Requesting a writ of mandamus is to request that a court compel a government body to perform or to refrain from performing a specific act.

• The duty to be compelled (or prevented) is to be of a public nature.
• The duty to be compelled (or prevented) must be imperative and not discretionary.
• Mandamus is typically not granted if the plaintiff can find relief by other means.

The purpose of mandamus is to remedy defects of justice. It lies in the cases where there is a specific right but no specific legal remedy for enforcing that right. Generally, it is not available in anticipation of any injury except when the petitioner is likely to be affected by an official act in contravention of a statutory duty or where an illegal or unconstitutional order is made. The grant of mandamus is therefore a matter for the discretion of the court.

Mandamus being a discretionary remedy, the application for it must be made in good faith and not for indirect purposes. The petitioner must satisfy the Court that they have the legal right to the performance of the legal duty as distinct from mere discretion by the authority. A mandamus is normally issued when an officer or an authority by compulsion of statute is required to perform a duty and that duty, despite demand in writing, has not been performed. In no other case will a writ of mandamus issue unless it be to quash an illegal order.

Summary from Wikipedia