A conflict between President Nicolas Maduro’s government and his increasingly defiant chief prosecutor was coming to a head Tuesday as Luisa Ortega Diaz announced she was boycotting a Supreme Court hearing on whether to lift her immunity from being tried for unspecified irregularities.

Ortega Diaz argued the outcome of Tuesday’s hearing was a foregone conclusion decided by the government that violates her legal right to defense and due process.

“I am not going to validate a circus that will stain our history with shame and pain,” she said at a news conference as the hearing was getting underway.

The case against her for alleged “serious errors” while in office was brought by a ruling-party lawmaker and could lead to her ouster.

National Guard troops and riot police took up positions outside the court building in Caracas, where protests against Maduro’s government have been raging almost daily for several months.

On Monday the government-stacked Supreme Court acted to strip a key power from Ortega by acting itself to impose her deputy: a loyalist who was sanctioned by the United States in 2015 for her role prosecuting some of Maduro’s most vocal opponents.

The decision to name Katherine Haringhton to the post effectively made her the nation’s No. 2 law enforcement official even though the constitution says the semi-autonomous chief prosecutor has the power to name her own deputy, with confirmation by congress.

Lawmakers on Monday had re-confirmed Ortega’s own choice as deputy after he was removed by the high court last week.

As Venezuela’s political crisis has deepened, Ortega has emerged as Maduro’s most-feared critic. In April the once-loyal leftist broke with the government over its decision to strip congress of its last powers, and she has made common cause with right-wing opponents in blasting Maduro’s plans to rewrite Venezuela’s 1999 constitution.

The Supreme Court has also attacked Ortega’s authority by throwing out her order for the former head of the National Guard to testify about alleged human rights abuses during the crackdown on the protests, which have left at least 80 dead. It has also limited her powers to investigate abuses, which are shared with the nation’s ombudsman.