Silvio Berlusconi's lawyers asked an Italian court Tuesday to uphold an immunity law that has shielded the Italian premier from a corruption trial in Milan — a decision that could determine the future of his government.

The Constitutional Court in Rome was hearing arguments Tuesday before deliberating over whether the legislation complies with the Italian constitution, but it was unclear when the court's 15 judges would issue a ruling. Berlusconi lawyer Gaetano Pecorella suggested, however, that a decision could be made this week.

A rejection of the legislation could lead to pressure on Berlusconi to resign and possibly to early elections. A ruling upholding the immunity law might give Berlusconi a boost at a time when he is under attack amid a sex scandal.

Berlusconi, a billionaire businessman-turned-politician with a history of legal troubles stemming from his private interests, said this week that "nothing will make us betray the mandate that Italians have given us."

The law in question — passed in 2008 after Berlusconi took power in his third stint as premier — grants immunity to the premier, the Italian president and the two speakers of Parliament while in office.

It was spearheaded by Berlusconi ally Justice Minister Angelino Alfano, and passed as Berlusconi was on trial in Milan on charges that he bribed a British lawyer for false testimony. As a result the trial was suspended, drawing accusations that the legislation was tailor-made for the premier.

The law, however, only freezes the statute of limitations while the officials are in office, leaving the possibility of them being prosecuted after their terms end. Critics argue that the law violates the principle that all are equal before the law.

Berlusconi has denied the corruption charges, and the Milan proceedings could resume if the court determines the immunity law is unconstitutional. His lawyers have suggested Berlusconi might have to resign since he would be unable to do his job while on trial.

"It is not possible to serve at the same time and effectively in the double role of top official and defendant," lawyer Piero Longo told the court.

"A high-ranking official must be available for any event that might require his political attention," Longo said. "In the global geopolitical system we live in today, sudden crises or dramatic events — both on the international scene and in our beloved country — are as unforeseeable as they are physiologic."

Another Berlusconi lawyer, Niccolo Ghedini, said that while all Italians are equal before the law, the application of the law isn't necessarily equal for all, meaning that the procedures in which a trial takes place might change without this violating the constitution.

The 2008 immunity law amended earlier legislation passed by Berlusconi's allies but rejected by the Constitutional Court in 2004.

In the Milan trial, Berlusconi was accused of ordering the 1997 payment of at least $600,000 to British lawyer David Mills in exchange for the lawyer's false testimony at two hearings in other corruption cases in the 1990s.

While Berlusconi's portion of the trial was frozen when the immunity bill was passed, the proceedings continued for Mills. In February, he was convicted of corruption and sentenced to 4 1/2 years in prison. Mills, the estranged husband of Britain's Olympics Minister Tessa Jowell, has maintained his innocence and said he would appeal.

In his past legal woes, Berlusconi has either been acquitted or cleared because the statute of limitations had expired.

He has always maintained his innocence and depicted himself as a victim of left-leaning magistrates.

But last week, a judge in a different case handed down a devastating ruling against Berlusconi's holding company Fininvest. The court ordered Fininvest to pay $1 billion to a rival for its 1990s takeover of the Mondadori publishing house.

The civil damage award stems from a case in which three Berlusconi associates were convicted of corrupting a judge so he would overturn a ruling that had gone in favor of industrialist Carlo De Benedetti and against Berlusconi for control of Mondadori.

Due to the reversal, Mondadori is now part of Fininvest. The company said the ruling is unjust and it will seek to suspend the judgment pending an appeal.

While Berlusconi wasn't prosecuted in the case, the court said he was "co-responsible" in the civil portion as head of Fininvest.

Berlusconi said Monday he was astounded by the Mondadori judgment and insisted the government would "carry out its five-year mission and nothing will make us betray the mandate that Italians have given us."