Story highlights Berlusconi's conviction is upheld, but the impact on his political career is unclear

Italy high court: A lower court should reconsider barring him from public office

The former prime minister was convicted of tax evasion last October

Italy's high court has upheld a prison sentence for former Prime Minister Silvio Berlusconi in a tax fraud case.

The court Thursday said it supported a lower court's four-year prison sentence for Berlusconi.

Three years of that sentence are covered in an amnesty aimed at cutting down on prison overcrowding, effectively reducing Berlusconi's sentence to one year.

The high court also ordered a lower court to reconsider whether Berlusconi, 76, should be banned from public office -- a controversial issue that could play a key role in the country's political future.

A lower court convicted Berlusconi of tax evasion last October, sentencing him to four years in prison and barring him from public office for five years. In May, an Italian appeals court in Milan upheld that decision

The former prime minister can't appeal the high court's decision in the case.

But it's unlikely he'll spend time behind bars, because of his age and the shortness of the sentence.

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Berlusconi is a member of Italy's Senate and therefore enjoys immunity from any type of arrest.

The Senate would have to vote to have his immunity lifted in order to serve any sentence.

Berlusconi, who served on and off as prime minister between 1994 and 2011, is one of the most colorful and controversial figures in the lively history of Italian politics.

For years, he has been entangled in fraud, corruption and sex scandals that have often reached Italian courts.

In June, a panel of judges sentenced Berlusconi to seven years in prison for abusing power and having sex with an underage prostitute. Berlusconi's attorney told reporters he plans to appeal that conviction.

Undaunted by the court battles, Berlusconi has not only launched appeals, but in December made two significant announcements: his engagement to 27-year-old Francesca Pascale, and then, his political comeback.

In Italy's February elections, the three-time prime minister appealed to Italian voters by denouncing the unpopular austerity policies of technocrat Mario Monti.

For all his critics, Berlusconi won almost 30% of the vote in February and remains an influential figure in Prime Minister Enrico Letta's fragile coalition government.