Italy's top court rules this week on whether a law granting immunity to Prime Minister Silvio Berlusconi violates the constitution, in a politically charged verdict that could reopen criminal trials against him.
One of the first measures passed by parliament since Berlusconi returned to power for a third time last year was a law giving him immunity from prosecution while in office.
The law's immediate effect was to halt existing legal proceedings against the 73-year-old conservative businessman.
But prosecutors in those cases have lodged an appeal with the Constitutional Court, arguing that the measure violates a number of principles enshrined in Italy's constitution, including that all citizens are equal before the law.
The court meets on Tuesday and is expected to give its verdict by Thursday. Should it rule the law unconstitutional, the trials against Berlusconi would resume.
Critics say the immunity law, which also covers the head of state and speakers of both chambers of parliament, was tailored to rid media tycoon Berlusconi of legal headaches.
The prime minister says magistrates have hounded him since entering politics 15 years ago, and that the law allows him to govern without being "distracted" by the judiciary.
Presenting his case to the court, the state's lawyer for the premier's office said overturning the law would do "irreparable damage" and could even lead to Berlusconi's resignation.
Political analysts say Berlusconi is unlikely to step down if the court rules against him but that he would be considerably weakened at a time when his popularity has been hurt by a sex scandal revolving around prostitutes invited to his residence.
"Certainly we would be talking about a much weaker government. Not only would existing trials restart but it would be a free-for-all in terms of new investigations that might pop up," said Franco Pavoncello of John Cabot University in Rome.
The highest-profile trial suspended as a result of the law has seen Berlusconi charged with paying British lawyer David Mills $600,000 in 1997 from alleged secret funds held by his family-owned Mediaset to withhold incriminating details of his business dealings.
Mills was sentenced in February to four years and six months in prison for corruption. He, like Berlusconi, says he is innocent and is appealing the verdict.
The fate of two other cases against the prime minister also depends on the court's ruling.
The Constitutional Court, whose verdict is final, is made up of 15 judges, appointed in different ways. Five of them have a clear political affiliation -- three are close to Berlusconi's party, while the other two are linked to the centre left.
A Milan court dealt Berlusconi a blow at the weekend when it ordered his Fininvest holding to pay 750 million euros in damages to CIR for corrupting a judge in a 1990s battle to take over Italy's biggest publishing group.
Berlusconi has already been cleared of criminal charges in that case. His aides said the Milan ruling was part of a "concentric attack" on the prime minister.