Former Venezuelan President Nicolas Maduro is immune from prosecution because he is a head of state, according to his lawyer, who filed a petition for his charges to be dismissed.

"No American court has ever presided over the criminal trial of a foreign leader who was recognized by their own country as the sitting head of state at the time the charges were brought," Barry Pollack, a lawyer for Maduro who filed the declaration in federal court on Wednesday, said.

He said heads of state are "exempt from the criminal process of any national court" except in their own country, reflecting "a rule older than the common law." "That immunity flows not from goodwill that can be withdrawn on a whim, but from the perfect equality and absolute independence of sovereigns," he said.