Opponents accuse Mr Berlusconi of using legislation to shorten his trials
Dozens of Italian judges have walked out of courts in protest at PM Silvio Berlusconi's judicial reforms, which they call destructive.
The judges left ceremonies to mark the start of the judicial year as a government official began speaking.
They say they are fed up with Mr Berlusconi's "threats" against them.
The prime minister, who faces two court cases, says judges are "communists" who are trying to depose him through the legal system.
The Italian parliament - dominated by Mr Berlusconi's supporters - is currently examining the legislation, which includes provisions to curb the length of legal cases.
Opponents say it would in effect stop these two trials, but the prime minister denies it is tailor-made to do this.
In cities such as Palermo, Naples and Milan, magistrates walked out carrying copies of the constitution, returning only when the government speech had ended.
In Rome, at least 50 judges and prosecutors left the courts, Italian TV reported.
"An execution squad, sewer, cancer, metastasis - these are some of the words that the prime minister and his deputies have used to describe us," Reuters news agency quoted magistrates' union spokesman Gioacchino Natoli as saying.
"We don't want to be subject to this continued aggression."
The trials against Mr Berlusconi resumed earlier this month after an immunity law protecting him was overturned.
He is accused in a corruption trial involved UK tax lawyer David Mills, who was convicted last year, and is also facing charges of tax fraud and false accounting over the purchase of TV rights by his Mediaset group.