Grave abuse of discretion: "By grave abuse of discretion is meant simply capricious or whimsical exercise of judgment that is patent and gross as to amount to an evasion of positive duty or 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."

"X x x.

By grave abuse of discretion is meant simply capricious or whimsical exercise of judgment that is patent and gross as to amount to an evasion of positive duty or 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.[29] Under this definition, a court is without power to directly decide matters over which full discretionary authority has been delegated. But while this Court has no power to substitute its judgment for that of Congress or of the President, it may look into the question of whether such exercise has been made in grave abuse of discretion.[30] A showing that plenary power is granted either department of government, may not be an obstacle to judicial inquiry, for the improvident exercise or abuse thereof may give rise to justiciable controversy.[31]

x x x."

Read:

[G.R. No. 141284. August 15, 2000]

INTEGRATED BAR OF THE PHILIPPINES, petitioner, vs. HON. RONALDO B. ZAMORA, GEN. PANFILO M. LACSON, GEN. EDGAR B. AGLIPAY, and GEN. ANGELO REYES, respondents.