High profile journalist Maria Ressa went on trial Tuesday on criminal libel charges in the Philippines. She and her supporters say the case is nothing more than a government attempt to silence a free press.

Ressa and press freedom advocates around the world believe controversial President Rodrigo Duterte's government had the journalist arrested in retaliation for critical reporting on the website Rappler, which Ressa founded.

That reporting includes coverage of the deadly war on drugs launched by Duterte, which has led to more than 5,000 people being killed over the last three years. That is just the official tally -- in reality the toll could be many thousands more.

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The policy has drawn international condemnation, and as CBS News correspondent Holly Williams reported on Tuesday, Duterte himself has previously suggested that some journalists are legitimate targets for assassination, and called reporters "spies."

Ressa was named one of Time magazine's people of the year in 2018 for her journalism. If convicted, she could face several years in prison.

As reported last month in a CBSN Original on Ressa, the journalist is facing a total of 11 criminal charges in her home country.

"I don't know what's next," she told CBS News in June.

Earlier this month, a London-based firm announced that international human rights lawyer Amal Clooney was to spearhead a team of law experts providing assistance to Ressa's legal team in Manila. In the statement from the Doughty Street Chambers firm, Clooney called Ressa "a courageous journalist who is being persecuted for reporting the news and standing up to human rights abuses."

Clooney, along with associates Caoilfhionn Gallagher and Kathrine O'Byrne, were to "act with a team of international lawyers as counsel to" Ressa, according to Doughty Street Chambers.

Human rights lawyer Amal Clooney speaks on September 12, 2016 in Stuttgart. Clooney seeks international attention for the fate of the Kurdish religious community Yazidis in Iraq. Bernd Weissbord/AFP/Getty Images

Clooney has backed a number of high-profile causes, from refugees in the U.S. to students demanding gun law reforms. But Ressa is not facing charges anywhere but in her native country, and it remained unclear how much practical help Clooney and her team might be able to provide the journalist as she battles the charges in Philippine courts.

"We will pursue all available legal remedies to vindicate her rights and defend press freedom and the rule of law in the Philippines," Clooney said in the statement released by the law firm.

The lawyers were to work in conjunction with another international law team in Washington D.C., including Daniel Feldman, a former U.S. Deputy Assistant Secretary of State for South and Central Asia.

Doughty Street Chambers said Clooney's team would "coordinate as necessary with domestic counsel in Manila."