Silvio Berlusconi paid the Sicilian mafia "conspicuous sums" of protection money in the 1970s, Italy's highest appeal court said in a ruling, published in part by Italian media Wednesday.
The former premier, who has long been dogged by allegations of mafia ties, was described by the court as "a victim who acted through necessity" to protect himself and his family in a period of violence and instability in Italy.
He "paid conspicuous sums for his security and that of his family," it said.
The 146-page document released Tuesday explained the court's decision in March to overturn the conviction of one of Berlusconi's close aides, Senator Marcello Dell'Utri, for association with organised crime.
The Sicilian "mediated" between Berlusconi and the crime group, it said.
Dell'Utri was "the author of an agreement of a protective and collaborative nature between Berlusconi and the mafia," the court said, though it overturned his conviction because the magistrates had failed to prove part of the case.
The pact with Cosa Nostra is also thought to have lead to Berlusconi hiring a known gangster, Vittorio Mangano, at his Arcore villa in the mid-1970s -- allegedly as a stableman. Mangano was later convicted of murder.
Dell'Utri was sentenced in 2004 to nine years' imprisonment over links to leaders of the Cosa Nostra. The Palermo court of appeal confirmed the conviction in June 2010 but reduced the sentence to seven years.
During the appeal trial in December 2009 mafia turncoat Gaspare Spatuzza had accused the senator of having acted as a middle man between the Cosa Nostra and the political world, but his testimony was widely discredited.
Berlusconi, ousted from power in November amid a series of sex scandals and a financial crisis, is currently a defendant in three trials and is accused, among other things, of fraud and for paying for sex with an underage girl.
Despite some initial convictions and lingering accusations of alliances with convicted crooks, all cases against him have been won on appeal or have expired.
In February a court in Milan threw out bribery charges against Berlusconi under the statute of limitations after a five-year trial, in another judicial victory for the former prime minister.