G.R. No. L-32715 and G.R. No. L-33908, September 30, 1977
NATIONAL WATERWORKS AND SEWERAGE AUTHORITY, petitioner, vs. NWSA CONSOLIDATED UNIONS, et al., and the COURT OF INDUSTRIAL RELATIONS, respondents.

FACTS

In two consolidated cases, the National Waterworks and Sewerage Authority (NWSA) sought to set aside orders of the Court of Industrial Relations (CIR). In G.R. No. L-32715, the CIR ordered NWSA to deposit P34,581.56 as salary adjustment differentials for six monthly-salaried employees (Amado L. Guevara, et al.). In G.R. No. L-33908, the CIR ordered a deposit of P12,037.18 for employee Simeon Chongco. The claims were based on the Supreme Court’s 1964 ruling in NWSA vs. NWSA Consolidated Unions (G.R. No. L-18938), which held that employees made to work seven days a week prior to June 30, 1957, were entitled to a salary adjustment equivalent to 7/5 of their pay starting July 1, 1957, pursuant to Republic Act No. 1880 .
The petitioners argued before the CIR that the claimants, being monthly-salaried employees, were not entitled to such adjustments under R.A. No. 1880 , which they contended applied only to daily-paid workers. They also contested the mathematical computation of the awards and, in the first case, raised a procedural issue regarding the timeliness of their motion for reconsideration.

ISSUE

The primary issue was whether the monthly-salaried employee-claimants were entitled to the salary adjustment benefits mandated by the Supreme Court’s 1964 ruling in G.R. No. L-18938, which interpreted R.A. No. 1880 .

RULING

The Supreme Court affirmed the CIR orders. On the substantive issue, the Court held that the 1964 ruling in G.R. No. L-18938 was conclusive and binding. In that prior case, the Court had already interpreted R.A. No. 1880 and explicitly ruled that the salary adjustment applied to “employees and laborers” of the NWSA who were required to work seven days a week during the relevant period. This broad term encompassed both daily-paid and monthly-salaried personnel. The principle of conclusiveness of judgment or “res judicata” applied to the interpretation of the law established in the earlier case, barring NWSA from re-litigating the same legal question. The Court emphasized that labor laws are to be construed liberally in favor of the worker.
Regarding the procedural challenge in G.R. No. L-32715, the Court found no grave abuse of discretion in the CIR’s finding that NWSA’s motion for reconsideration was filed out of time, as the record supported this conclusion. On the computation of awards, the Court upheld the CIR’s reliance on the reports of its court examiner. In the absence of a specific and substantiated objection from NWSA pointing out errors in the mathematical calculations, the examiner’s report, which was subject to verification by both parties, was deemed prima facie correct. The burden to disprove the report lay with NWSA, which it failed to discharge. Therefore, the CIR did not err in ordering the deposit of the specified amounts for the claimants’ benefits.