Italy's constitutional court this evening rejected an attempt by Silvio Berlusconi to block a tax fraud conviction from October.
The ruling clears the way for a final verdict this year.
Berlusconi's lawyers had challenged a ruling in Milan last year that sentenced the 76-year-old media tycoon and leader of the centre-right to four years in prison with a five-year ban on holding public office.
It found him complicit in tax fraud at his Mediaset empire.
His lawyers argued that the case was flawed because judges had refused to allow a delay when Berlusconi claimed he was unable to attend a hearing in March 2010 because of his responsibilities as prime minister at the time.
The constitutional court ruled that it was up to the judges of the original case to rule on whether Berlusconi's claim was allowable or not.
It also noted that he had been given several opportunities to agree an acceptable court date.
Berlusconi said the ruling would have no effect on his support for Prime Minister Enrico Letta's government.
Berlusconi's People of Freedom party is one of Mr Letta's main backers in a broad, right-left coalition.
"Today's constitutional court decision, which goes against common sense and all the preceding jurisprudence made by the very same court, will not have any influence on my personal commitment to support the government with loyalty and conviction," Berlusconi said in a statement.