The Italian prime minister is expected to face a renewed corruption trial after a court annulled his immunity from prosecution.
Berlusconi faces resumption of trial
The country's top court threw out a controversial law granting Silvio Berlusconi immunity as long as he remained in office.
The BBC's David Willey in Rome says the law was rushed through last year to save Mr Berlusconi the indignity of standing in court while EU president.
Critics said the bill was an overt attempt to scupper the trial.
They had challenged it on the grounds that it breached Italian equality legislation and put Mr Berlusconi "above the law".
The constitutional court agreed and struck down the law, which also applied to the holders of four other top Italian public positions.
The introduction of the law halted the trial, which was under way in Milan, and which Mr Berlusconi had already attended to give evidence in his defence.
Niccolo Ghedini, one of the prime minister's lawyers, told the Associated Press the trial in Milan was expected to resume in about two months with a new panel of judges.
TRIALS OF SILVIO BERLUSCONI
2004: Immunity law annulled by constitutional court
2003: Charges of bribing judges suspended with passing of immunity law
2002: False accounting charges dropped under new statute of limitations
2000: Acquitted of charges of bribing tax inspectors
1998: Guilty of illegal party financing, prison ordered but cancelled after appeal
1997: Guilty of false accounting, sentence dropped in amnesty, acquitted in 2000
A former anti-corruption judge, Antonio di Pietro, welcomed the ruling.
"It's good news because we have always said that this law is unconstitutional and immoral," he said.
But there was anger among some supporters of the prime minister.
"Surely a liberal would not have issued such a ruling. Only a communist could conceive it," said Carlo Taormina, a close ally of Mr Berlusconi and a lawmaker for his Forza Italia party.
Others allies were more circumspect.
"We don't agree with this ruling but we respect it," said Renato Schifani, party whip and the architect of the immunity legislation.
Mr Berlusconi - who is Italy's richest man - was accused of attempting to bribe a judge during a business takeover deal.
Prosecutors alleged he was trying to stop a rival firm taking over state-owned food group SME in the 1980s.
Mr Berlusconi says the charges are politically motivated, and that left-wing magistrates in Milan are trying to undermine him.
Mr Berlusconi is believed to be worth more than 10 billion euros ($13 billion).