G.R. No. 93054 - Ordillo vs. Commission on Elections

On January 30, 1990, pursuant to Republic Act No. 6766, the provinces of Benguet, Mountain Province, Ifugao, Abra, Kalinga-Apayao, and the city of Baguio held a plebiscite on the Organic Act for the Cordillera Autonomous Region (CAR).
Only Ifugao voted in favor by a slim majority of 5,889 votes; the other units rejected the measure by 148,676 votes.

February 14, 1990: COMELEC Resolution No. 2259 declared that, since only Ifugao voted “yes,” that province alone ratified the Organic Act. Simultaneously, the Secretary of Justice issued a memorandum confirming that Ifugao “alone, legally and validly constitutes the CAR.”
February 5, 1990: The Executive Secretary authorized winding up of the Cordillera Executive Board and Assembly created under E.O. No. 220.
March 8, 1990: Congress passed Republic Act No. 6861 setting regional elections in the CAR of Ifugao for March 1991.
March 9 and March 30, 1990: Petitioners filed with COMELEC to declare non-ratification of the Organic Act; on March 30, the President issued Administrative Order No. 160 abolishing the Cordillera Executive Board, Assembly, and related offices.

Petitioners, comprising regional officials and residents, argued that under the Constitution and RA 6766 an autonomous region must consist of multiple constituent units, not a single province.
They prayed for:

Nullification of COMELEC Res. 2259, the Justice and Executive Secretary memoranda, A.O. 160, and RA 6861, and enjoining their implementation and spending;
Declaration that E.O. 220 remains in force until a valid organic law is enacted and ratified.

Can a single province (Ifugao) validly and legally constitute the Cordillera Autonomous Region under the 1987 Constitution and RA 6766?
Are COMELEC Resolution No. 2259, the Secretary of Justice and Executive Secretary memoranda, Administrative Order No. 160, and Republic Act No. 6861 valid, or must they be annulled?