Manila, Sept. 16 -- Retired Supreme Court Chief Justice Artemio Panganiban cited the landmark Avelino v. Cuenco ruling on Wednesday as he urged the Senate to look beyond abstract arithmetic in determining the votes needed to convict Vice President Sara Duterte.

Speaking as an amicus curiae (friend of the court), Panganiban questioned whether senators who had not examined the evidence or heard the witnesses should be allowed to vote in the impeachment trial.

"Reality, sometimes, Your Honors, changes the denominator in mathematics. In the same way, constitutional interpretation cannot always stop at abstract mathematics," he said.

Panganiban acknowledged that two-thirds of the Senate's 24 members equals 16. He, however, told senator-judg...