MANILA- The Philippines' withdrawal from the International Criminal Court (ICC) has no legal basis and was just a "whimsical and arbitrary" decision of President Rodrigo Duterte.

This was the argument of petitioners seeking to declare the Philippines' exit from the ICC as invalid as the Supreme Court held oral arguments on the matter on Tuesday.

"The executive has no...legal basis for the withdrawal other than the President's whimsical and arbitrary decision," lawyer Romel Bagares, counsel for petitioners, told the top court.

Bagares represents the Philippine Coalition for the International Criminal Court (PCICC), which is seeking to invalidate the Philippines' withdrawal from the ICC along with minority senators.

Senators Francis "Kiko" Pangilinan, Franklin Drilon, Bam Aquino, Risa Hontiveros, Leila de Lima, and Antonio Trillanes IV filed a pleading in March seeking to declare the Philippines' withdrawal from the ICC invalid after the President moved to pull out the Philippines from the ICC in the same month.

The lawmakers argued that the withdrawal should be invalidated for lack of concurrence of the Senate by a two-thirds vote.

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Bagares explained that under the charter, treaties or international agreements shall only be valid and effective unless concurred in by at least two-thirds of all the members of the Senate.

"The Executive cannot unilaterally withdraw from a treaty without violating the Constitution," Bagares argued. "Such withdrawal, therefore, is a violation of separation of powers."

Malacañang previously said it was confident that the top court will respect the government's decision to withdraw the Philippines from the ICC since the President is the “chief architect” of the country’s foreign policy.

Presidential Spokesperson Harry Roque had said that it cannot be alleged that there was grave abuse of discretion amounting to lack or excess of jurisdiction.

"You cannot allege that on matters of foreign affairs. The courts will always defer to the executive on matters of foreign affairs," he said.

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The Philippines signed the Rome Statute on Dec. 28, 2000 and ratified and endorsed it in August 2011, during the time of Duterte’s predecessor, the then President Benigno "Noynoy" Aquino III.

Created through the 1998 Rome Statute, the ICC has jurisdiction over 124 of its members, including the Philippines.