G.R. No. 150253 ; November 30, 2006
Davao Light and Power Corporation, Inc., Petitioner, vs. Antonio G. Diaz and Francisco P. Tesorero, Respondents.

FACTS

Petitioner Davao Light and Power Co., Inc. (DALIGHT) filed two applications with the Board of Energy (BOE), later the Energy Regulatory Board (ERB), for approval of the sound value appraisal of its properties to set its rate base. The first application, for properties as of October 9, 1981, was docketed as BOE Case No. 82-684. The BOE approved a reduced amount in 1983. Respondents Diaz and Tesorero, consumers, appealed to the Supreme Court in G.R. No. 69592. On May 8, 1990, the Court further reduced the approved sound value, notably excluding certain generators which DALIGHT was allegedly precluded from replacing under P.D. No. 40.
While G.R. No. 69592 was pending, DALIGHT filed a second application for properties as of December 14, 1984, docketed as BOE Case No. 85-103. The ERB approved this appraisal on September 18, 1989. In 1995, respondents petitioned the ERB to nullify this 1989 decision, arguing it was void for including the same generators the Supreme Court later ordered excluded in its 1990 ruling. The ERB and later the Court of Appeals dismissed their petition, prompting this appeal.

ISSUE

Whether the Court of Appeals erred in not declaring the ERB’s September 18, 1989 Decision void for including assets that the Supreme Court, in a related but later-promulgated decision (G.R. No. 69592), had ordered excluded from the rate base.

RULING

The Supreme Court denied the petition and affirmed the Court of Appeals. The legal logic rests on the finality and immutability of judgments and the specific timing of the decisions involved. The ERB’s September 18, 1989 Decision in the second appraisal case (for the 1984 rate base) had long become final and executory, as no timely appeal was taken from it. It is a fundamental rule that a final judgment can no longer be altered.
Critically, the Supreme Court’s ruling in G.R. No. 69592, which ordered the exclusion of the generators, was promulgated on May 8, 1990. This decision pertained specifically to the first appraisal case for the 1981 rate base. It could not retroactively invalidate the separate and already-final 1989 decision for the 1984 rate base. Each appraisal application constitutes a distinct proceeding with its own factual cutoff date and subject matter. The 1990 ruling established a legal principle for future guidance but did not automatically void a prior final judgment in a different case. Therefore, the ERB did not commit grave abuse of discretion, and the 1989 decision stands.