It was an interesting piece of legal doublethink: although the law was equal for all, said Niccolo Ghedini, the wily and cadaverous personal lawyer for Silvio Berlusconi, “application of the law is another matter”.

When Patrizia D’Addario, a prostitute from Bari, alleged this year that the Prime Minister had slept with her on the night of the US election, Mr Ghedini said that his boss had not committed a crime because he was merely “the end user”. A draft law penalising male customers of prostitutes was postponed.

Mr Ghedini is also a deputy for Mr Berlusconi’s ruling party, the People of Liberty, and has a role in framing laws and in defending the Prime Minister. No one has challenged this obvious conflict of interest. It is taken for granted that all aspects of life in Italy are politically coloured — including the Constitutional Court.

Five of the 15 judges ruling on the immunity law are appointed by parliament. Three of those are on the Centre Right, two on the Centre Left. In May Mr Berlusconi was accused by the opposition of trying to nobble the judges when he dined with two of them. Only one, Maria Rita Saulle, 73, is a woman — and whether she shares the distaste felt by many Italian women for Mr Berlusconi over his sex scandals is not known.

For the Prime Minister’s supporters the challenge to the immunity law is part of a fiendish plot. People of Liberty MPs claim that there is a “subversive plan to challenge the will of the people”.

No conspirator forced Mr Berlusconi to go to the 18th birthday party in Naples of Noemi Letizia, an aspiring model, prompting his wife to demand a divorce. No plotter forced him to go to bed with Ms D’Addario, who last week told millions of Italian television viewers that he knew “perfectly well” she was an escort girl.

Equally, the corruption allegations he is likely to face if the immunity law is lifted stem from his own actions. If Mr Berlusconi’s immunity is lifted and he faces prosecution for evading taxes, and for trying to bribe centre-left senators to desert the fragile Government of Romano Prodi, it will be because prosecutors believe that he has broken the law.

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