A petition has been presented to Italy’s highest court requesting a referendum to overturn the law that grants Italian Prime Minister Silvio Berlusconi immunity from criminal prosecution while in office.

Anti-corruption magistrate Antonio Di Pietro led the effort to collect 1 million signatures, twice the amount needed to force a referendum.

Three-time Prime Minister Berlusconi has been hounded by prosecutors for years, but has never been convicted. Last year, Berlusconi pushed legislation through Parliament granting immunity to the four highest office-holders in the country from prosecution.

Two corruption trials are currently on hold against Berlusconi while the law remains in effect.

Italy’s constitutional court must check the validity of the names on the petition. That process could take several months.