Former senator Leila de Lima is willing to sue Senator Ronald "Bato" dela Rosa over allegations of coercing ex-convict and self-confessed drug user Rolan "Kerwin" Espinosa to implicate her in the illegal drug trade, resulting in her unjust detention.

De Lima revealed in an interview on Monday that she was already discussing the filing of charges with her lawyers.

"I'm inclined to file cases against Senator Bato," De Lima said. "Here we are, there is a witness who directly, personally, under oath, implicated him when before there was none."

Espinosa, who was instrumental in the arrest of then-sitting senator De Lima, told the House committee on Friday that he was only pressured and threatened by Dela Rosa, who was then spearheading Duterte's anti-drug campaign, to pin De Lima and Cebu-based businessman Peter Lim in the narcotics trade.

To recall, Espinosa testified in a series of Senate probes in 2016 implicating De Lima as part of the illicit drug trade inside the National Bilibid Prison in Muntinlupa City during her stint as Justice secretary.

His allegations resulted in the six-year-long detention of De Lima.

However, in the recent House inquiry into alleged extrajudicial killings (EJK) of the previous administration, Espinosa admitted that she wrongfully accused De Lima out of fear for his life.

The ex-convict elaborated that Dela Rosa intimidated him with a fate similar to that of his father, former Albuera, Leyte, mayor Rolando Espinosa, who was shot dead in his cell in November 2016 amid allegations of involvement in narcotics.

The father and son were both included in Duterte's narco-list.

An enraged Dela Rosa denied the allegation of Espinosa, whom he called a "liar" and threatened with a punch in the face.

De Lima said Espinosa's explosive revelation came as no surprise as she knew all along that he was merely coerced.

"When he appeared before the Senate hearing, I knew that it was a gunpoint, coerced because it was just barely two weeks after the assassination of his father," she stressed.

Meanwhile, Batangas Representative Gerville Luistro is confident that the testimony of Espinosa has nothing to do with the 2025 polls, in which he will vie as Albuera mayor.

"He just got an opportunity now. We have to understand that the quad comm [inquiry] started recently. It just so happened that it coincided with the [election] filing," she said in Filipino in an interview on Monday.

According to Luistro, Espinosa's testimony requires a "deeper investigation" not only to substantiate the filing of charges but also to assist the quad comm of making a "correct and balanced" conclusion.

Moreover, she implied it could also be submitted to the International Criminal Court, which is probing Duterte's alleged EJK, given that it was made under oath, which has the effect of a sworn statement.

"What is clear was there should be no killing. Because EJK is synonymous with summary execution. Even if there is no hearing, even if there is no case, even if they do not resist arrest, the victims were killed and that is not only legally wrong but also morally wrong," she lamented.