Silvio Berlusconi's lawyers for the removal of the presiding judge in a corruption trial against the premier, reported dpa.
The ruling by the appeals court comes amid controversy in Italy over legislation propounded by the centre-right government which critics say is solely aimed at protecting Berlusconi from legal action.
Berlusconi is currently on trial on charges he ordered payment in 1997 of at least 600,000 dollars to his co-defendant, British lawyer David Mills, in exchange for false testimony at two Berlusconi trials in the 1990s.
Both defendants deny the charges, and Berlusconi's lawyers, who accuse Judge Nicoletta Gandus of being biased against their client, last month asked for her removal.
Italy's lower house of parliament voted last week to pass a controversial immunity bill put forward by the government which protects top public officials, including the prime minister and president, from prosecution.
The bill is expected to be passed by the upper house, where Berlusconi and his allies also enjoy a solid majority, in September.
Berlusconi, a billionaire media-baron-turned-politician has repeatedly accused those he describes as left-wing extremist elements of the judiciary of waging a political vendetta against him.