Italy's second-biggest opposition party on Wednesday filed a petition aimed at rescinding a controversial law granting immunity from criminal prosecution to the country's top four officials including Premier Silvio Berlusconi.
Presenting a million signatures to the Cassation Court in support of a referendum, Italy of Values (IDV) leader Antonio Di Pietro claimed the so-called Alfano Law - named after Justice Minister Angelino Alfano - breached constitutional safeguards ensuring equality before the law.
''The Alfano Law is unconstitutional because it introduces a double standard establishing that the four highest state officials can't be tried even if they kill their mothers,'' said the former Milan graftbuster.
The Cassation Court, Italy's highest court of appeal, will now deliberate on whether the referendum request is valid.
This process normally takes a few months.
The law is a revised version of a 2004 law which was shot down by the Constitutional Court.
The government claims the new version has been changed to address the concerns that led to the dismissal of the earlier one.
Berlusconi's critics say the July 2008 law was passed to halt two corruption trials against the premier.
The government says it brings Italy into line with other European countries.
Berlusconi has hailed it as ending what he calls persecution by politically motivated prosecutors.
Prosecutors in the trials have already asked the Constitutional Court for rulings on the law.
