G.R. No. 134577 , November 18, 1998.
SEN. MIRIAM DEFENSOR SANTIAGO and SEN. FRANCISCO S. TATAD, petitioners, vs. SEN. TEOFISTO T. GUINGONA, JR. and SEN. MARCELO B. FERNAN, respondents.

FACTS

The case involves a petition filed by Senators Miriam Defensor Santiago and Francisco S. Tatad against Senators Teofisto T. Guingona, Jr. and Marcelo B. Fernan. The specific factual antecedents of the main petition are not detailed in the provided text of Justice Vitug’s separate opinion. The provided text focuses solely on the legal principles articulated by Justice Vitug in his separate opinion regarding the Court’s expanded judicial power and its limits.

ISSUE

Whether the Supreme Court should exercise its expanded judicial power, under the 1987 Constitution , to review the actions of a co-equal branch of government in the context of this specific petition.

RULING

Justice Vitug, in his separate opinion, voted for the dismissal of the petition. He emphasized that while the 1987 Constitution expanded judicial power to include the determination of grave abuse of discretion by any government branch or instrumentality, this power is not without limits and must be exercised with judicial statesmanship. He reiterated the paramount doctrine of separation of powers. He expressed the view that when a question pertains to an internal affair of Congress or the Executive, judicial intervention is warranted only when there is a clear infringement or disregard of a specific constitutional proscription. In the instant case, he found “insufficient indication” to warrant judicial intervention under this standard.