Italy's top court debated on Tuesday whether a law granting immunity to Prime Minister Silvio Berlusconi violates the constitution, in a politically sensitive hearing that could reopen trials against him.
The Constitutional Court is expected to rule by Thursday, although Italian media said its 15 judges were split down the middle over the case and could delay their verdict by two weeks.
The controversial law shielding Italy's top four holders of state office, including Berlusconi, from prosecution was one of the first acts of the conservative leader's government when he won a third term in power last year.
Legal proceedings against him were halted as a result, including a trial in which he is accused of bribing British lawyer David Mills to give false testimony on his behalf to protect his businesses.
Two other cases, one accusing Berlusconi of tax fraud and false accounting over the acquisition of TV rights by his family-owned broadcaster Mediaset, and another involving allegations that he tried to corrupt opposition senators, have also been frozen.
Berlusconi denies any wrongdoing.
Prosecutors in those cases have appealed to the Constitutional Court, arguing that the immunity law violates principles enshrined in the constitution -- including that all citizens are equal before the law.
The court began debating on Tuesday morning. In an initial blow to the prosecutors who want Berlusconi's immunity lifted, it excluded some of them from the hearing on technical grounds -- although that has no clear bearing on the final ruling.
Analysts say the court's verdict will have strong political implications for Berlusconi. Should it rule that his immunity is unconstitutional, that would weaken him further at a time when his popularity has already been hurt by sex scandals.
A defiant Berlusconi said on Monday he would serve out his full term and his allies closed ranks around him.
"Berlusconi is firmly at the helm of the country, because that is the will of the voters gave him the mandate to govern for five years. The court's ruling will certainly not decide the fate of the government," said Planning Minister Gianfranco Rotondi.
Shortly before the start of the Constitutional Court's hearing, an old legal case came back to haunt the media tycoon when a Milan court imposed huge damages to his family's holding Fininvest for bribing a judge in a 1990s takeover battle.
Explaining its verdict, the Milan civil court said Berlusconi was co-responsible in the corruption case and it was up to Fininvest to pay the damages -- set at 750 million euros ($1.11 billion) -- because he ran it at the time.
Berlusconi had already been cleared in the case at the criminal level in 2007, so the court's accusation does not appear to carry immediate legal consequences for him.
But it put his media empire and business dealings back in the spotlight -- prompting allies to accuse the Milan judges of timing their verdict to influence the Constitutional Court.
The highest-profile trial suspended as a result of the immunity law saw Berlusconi charged with paying Mills $600,000 in 1997 from alleged secret funds held by 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.