A SENATOR critical of President Rodrigo R. Duterte has asked a trial court to allow her to post bail more than three years after her detention, citing weak evidence in her drug trafficking case.

In a 44-page motion dated June 15,, Senator Leila M. de Lima argued the testimonies against her so far have been based on hearsay.

She also said she wouldn’t be a flight risk because she respects the legal process as a senator.

Her bail would also uphold her “constitutional presumption of innocence, recognizing her right to due process and guarantee her appearance in court for the remainder of the trial.” Her temporary liberty would also let her serve her term as a senator, she said.

Ms. de Lima is on trial for allegedly abetting the illegal drug trade in the country’s jails when she was still Justice secretary. She was accused of extorting millions of pesos from a drug lord that she allegedly used to finance her senatorial campaign in 2016.

She has been jailed at the Philippine National Police Custodial Center in Camp Crame since February 2017. Several witnesses against Ms. de Lima were drug convicts serving time at the national penitentiary in Muntinlupa City.

The senator said the prosecution had failed to prove her alleged drug transactions by omitting details of the crime such as the specific drugs involved, the buyers and sellers and the place where the trade took place.

The US Senate early this year passed a resolution condemning the Duterte government for the wrongful detention of one of his staunchest critics.

The chamber approved Resolution 142, sponsored by Senator Edward J. Markey, on Jan. 9 urging the Philippines to release Ms. de Lima and drop charges against Maria A. Ressa, founder of news website Rappler. A trial court this week convicted her and the website’s former researcher for cyber-libel.

Drug-trafficking charges against Ms. de Lima “followed a history of criticizing extrajudicial killings in the Philippines and the Duterte administration’s anti-drug campaign,” according to the US resolution.

The US later barred the entry of several Philippine government officials responsible for Ms. de Lima’s prosecution including Senator Ronald M. de la Rosa, whose US visa was canceled.

Mr. Duterte in February said he was ending the visiting forces agreement with the US because of this, only to reconsider months later.

Mr. Duterte last year ordered authorities to ban several American senators who led the campaign in support of Ms. de Lima. — Vann Marlo M. Villegas