Silvio Berlusconi says he does not want to be 'distracted' from ruling
Italy's top court has begun reviewing a law that grants Prime Minister Silvio Berlusconi immunity from prosecution while in office.
The immunity law enabled Mr Berlusconi to withdraw from a number of court cases, including one where he was accused of corruption.
Opponents say immunity violates the principle that all citizens are equal before the law.
If the court rejects the law, trials against Mr Berlusconi could resume.
Observers say that though it may not topple the government, such a ruling could significantly weaken the prime minister at a time when personal scandals have already dented his support.
On Monday, following a bribery ruling against his Fininvest group, Mr Berlusconi pledged to serve out his five-year term, and his allies have also pledged their support.
Senator Lucio Malan, a member of Mr Berlusconi's People of Freedom party, said he was confident the law would not be changed.
"The Constitutional Court already ruled about a similar law a few years ago and the current law has been drawn keeping in account what the Constitutional Court said a few years ago," Mr Malan told the BBC's World Update programme.
"So I think that there won't be major problems with the constitutional court."
Soon after Mr Berlusconi came to power last year, a law was passed giving him immunity from prosecution while in office.
At the time he was facing a number of court cases, including one involving the British lawyer David Mills, in which Mr Berlusconi was accused of bribing him to give false evidence.
Mills, who said he was innocent, was sentenced in February to four years and six months in prison for corruption.
Now prosecutors from that case and two others have appealed to the Constitutional Court, saying immunity puts Mr Berlusconi above the law and should be reversed.
Mr Berlusconi says immunity allows him to govern without being "distracted" by the judiciary.
It is not clear exactly when the court will rule, though Italian media reports said a decision could come by Thursday.
The 15 high court judges are said to be almost evenly divided on the case, with five reportedly undecided. A ruling at the court requires a simple majority.
The immunity law also covers the head of state and speakers of both chambers of parliament.
Over the weekend, a court in Milan ordered Mr Berlusconi's holding company Fininvest to pay 750m euros (£694m) in damages for bribing a judge during a takeover bid for the publisher Mondadori.
The court said Mr Berlusconi, who was cleared of criminal charges in 2007, was "co-responsible" for the bribery in the civil case as head of Fininvest.