The French judiciary has been doing a good job of cleaning up politics. Last week Jacques Chirac, the former President, was ordered to stand trial for allegedly misusing millions of pounds of taxpayers’ money when he was Mayor of Paris. Two days earlier, Charles Pasqua, a veteran Cabinet Minister, was sentenced to a year in prison for corruption.

Enjoy the spectacle while it lasts, because President Sarkozy is about to perform his own judicial clean-up. He aims to abolish the system that made these cases possible.

Mr Sarkozy’s proposed reform would put an end to the institution of the independent juge d’instruction, or examining magistrate, which has existed for 200 years. Unhappy judges are trying to alert the country to the dangers of what the President depicts as a step towards efficient justice on the Anglo-American model.

On the face of it, the plan is laudable. Grave blunders in recent decades have given a bad name to examining judges. The independent investigators, created by Napoleon Bonaparte, are prone to abusing their powers, the argument goes. In the 19th century the solitary lawman was known as the most powerful man in France.

Mr Sarkozy’s plan will put prosecution fully in the hands of the state service, which deals already with all but the 5 per cent of cases that involve the most serious or sensitive crimes. Defendants will be given more rights and trials will be gladiatorial, with prosecutors and defence laying out their cases on equal terms, as in English law courts.

The problem arises from the fact that France has little tradition of an independent judiciary. The juges d’instruction, who are part detective and part judge, are the exception. Few believe that Mr Sarkozy will fulfil his promise to create an independent prosecution service. French procureurs take their orders from the Justice Minister, who reports to the President.

Over the past two decades, juges d’instruction have won the conviction of dozens of politicians and business figures.

The state prosecutor decided in September that the case against Mr Chirac should be thrown out. He was overruled by Xavière Simeoni, a dogged juge who has been investigating the charges. In the Pasqua affair, the prosecutors called for a lenient suspended sentence. Instead the trial judges accepted the examining magistrate’s argument for a real prison term.

In a variation on the theme, Mr Sarkozy now risks humiliation at the hands of a juge d’instruction. This involves the so-called Clearstream affair. Prosecutors staged the trial of Dominique de Villepin, the former Prime Minister, against the wishes of the investigating judge. It was widely assumed that Jean-Claude Marin, the Paris prosecutor, had been under orders from on high. If Mr de Villepin is acquitted of plotting to smear the President, the trial will look like a political show ordered by “Super Sarko”.

The corps of juges d’instruction are in open rebellion against Mr Sarkozy. Eva Joly, recently retired as one of the most feared investigators, wrote an open letter to him. “Who can still believe that the juge d’instruction is the most powerful man in France?” she asked. “The most powerful man in France is you.”

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