The impeachment case against Vice President Sara Duterte could go to waste if it reaches the 20th Congress, according to an election lawyer.

In a radio interview on Thursday, Atty. Romulo Macalintal said the Senate could terminate Duterte's case once the new session starts in June.

"Ibig sabihin pag natapos yung mga bagay-bagay na nakabinbin ngayon, ay ituturing na tapos na (It means when they do not finish the things that are pending now, they will treat it as done when they resume session)," he noted, adding that the resumption of the case would depend on the new set of senators that would get elected.

"Baka sasabihin ng [Team] Sara, tapos na yan kasi panibagong impeachment case na yan at sa ilalim ng Saligang Batas, hindi pwedeng magkaroon ng dalawang impeachment sa loob ng isang taon (Then it's possible that those Team Sara, they would say it's already done because it's a new impeachment case and under the Constitution, we cannot have two impeachment cases in one year)," he added.

Macalintal stressed that it is senators' duty to conduct an impeachment trial once the document from the House of Representatives reaches them.

"Dapat aksyunan kaagad ng Senado ang nasabing impeachment. Ibig sabihin yung trial dapat magsimula kaagad (The Senate should act immediately on the said impeachment. That means the trial should start as soon as possible)," Macalintal said.

Macalintal added that a special session would settle the issues surrounding Duterte's impeachment.

"Ang special session naman ay hindi lang limited sa legislative matters. Nagtataka lang naman ako kung bakit sinasabing hindi nga raw pwede (The special session is not limited to legislative matters. I am just wondering why they are saying that it's not possible)," he continued.

"Kung nagpatawag sana ng special session dapat e nandoon kasi napakalaki ng panganib na yang impeachment na yan kung yan ay mabalewala at tumawid sa susunod na Kongreso. Mababalewala yung trabahong ginawa ng Kongreso (If a special session had been called, then there should be there because it would be a danger if the impeachment case gets ignored. It will put the Congress' work to waste)," he added.

The House of Representatives impeached Duterte on 5 February on accusations such as budget anomalies, amassing unusual wealth, and an alleged threat to the life of President Ferdinand R. Marcos Jr.

At least 215 of its members, or more than one-third of the membership requirement, signed the complaint documents.

Congress is on recess from 6 February to 1 June; however, impeachment documents were transmitted to the Senate before the session adjourned.

Senate President Chiz Escudero earlier said that the impeachment trial of Duterte will most likely start in the 20th Congress when the new set of 12 senators is elected during the midterm polls.

Escudero also argued that the Senate requires the proper order before the impeachment trial can begin, dismissing claims that the Senate should "immediately" proceed with the trial.

He also noted that the 2011 impeachment of Ombudsman Merceditas Gutierrez took nearly two months before the trial began.

The 24 senators will serve as jurors in Duterte's impeachment trial, which could lead to her removal from office and a lifetime ban from any public post, effectively killing any hope of becoming president in 2028.

Duterte on Wednesday asked the Supreme Court (SC) to nullify an impeachment complaint against her, making it her first legal move to fight the case that could lead to her removal and a lifetime ban from public office.

In a petition to the SC, Duterte accused the House of Representatives of "grave abuse of discretion" when it "deliberately circumvented" a constitutional safeguard against more than one impeachment proceeding against the same official within a year.