What is gravely abused discretion?

The term "grave abuse of discretion" means such capricious or whimsical exercise of judgment which is equivalent to lack of jurisdiction.To justify judicial intervention, the abuse of discretion must be so patent and gross as to amount to an evasion of a positive duty or to a virtual refusal to perform a duty enjoined by law or to act at all in contemplation of law, as where the power is exercised in an arbitrary and despotic manner by reason of passion or hostility.[15] In Elma v. Jacobi,[16] the Supreme Court said that:

This error or abuse alone, however, does not render his act amenable to correction and annulment by the extraordinary remedy of certiorari. To justify judicial intrusion into what is fundamentally the domain of the Executive, the petitioner must clearly show that the prosecutor gravely abused his discretion amounting to lack or excess of jurisdiction in making his determination and in arriving at the conclusion he reached. This requires the petitioner to establish that the prosecutor exercised his power in an arbitrary and despotic manner by reason of passion or personal hostility; and it must be so patent and gross as to amount to an evasion or to a unilateral refusal to perform the duty enjoined or to act in contemplation of law, before judicial relief from a discretionary prosecutorial action may be obtained. [Emphasis supplied]

[15] First Women’s Credit Corp. v. Hon. Perez, 524 Phil. 305, 309 (2006).

[16] Elma v. Jacobi, G.R. No. 155996, June 27, 2012, 675 SCRA 20, 56-57.