|Berlusconi has been dogged by a variety of charges, including corruption [Reuters]
Italy's top court has partially struck down a law shielding the country's prime minister from legal action.
The constitutional court decided on Thursday that an immunity law that has allowed Silvio Berlusconi to avoid criminal prosecution while in office was "illegitimate".
The ruling means individual judges can decide whether Berlusconi can be forced to face trial.
Berlusconi's press office said in a statement that the prime minister "has not commented and has no intention of commenting" on the ruling.
The Italian news agency ANSA said the court ruled that Berlusconi could no longer automatically invoke a "legitimate impediment" claim exempting him and cabinet ministers from attending trials in progress because of their official duties.
However, defendants will still be able to seek a postponement due to "legitimate impediment".
Angelino Alfano, the justice minister, said the result confirmed that "judicial authorities have to take into account official duties."
However, Felice Casson, a former judge who is now a senator for the opposition Democratic Party, said in a statement that "basically the court has completely rejected the argument of the government and the premier's advisers".
Before the court's decision he had been characteristically confident, announcing during a visit to Berlin on Wednesday that "it really does not matter to me whether these trials are stopped or not".
The prime minister's battles with the law have marked his public life since he burst on to the political scene in the mid-1990s.
He has faced charges including corruption, tax fraud, false accounting and illegally financing political parties.
Although some initial judgments have gone against the tycoon, Berlusconi has never been definitively convicted.
If the constitutional court had scrapped the law entirely, two trials against Berlusconi that have been effectively frozen by the legislation would have likely been restarted, but it was not immediately clear whether attempts would be made now to reopen them.
The first is for alleged tax fraud by Berlusconi's Mediaset business empire and the second is for the suspected bribery of the prime minister's former lawyer David Mills.
The Corriere della Sera newspaper said on Thursday the ruling would most probably be insignificant because the trials "are so behind by now that they are almost certainly destined to run out of time" under the statute of limitations.