THE DECISION of the Italian authorities to issue charges of culpable homicide against Frank Williams and five others is good news only for the legal profession. Avvoccato Giorgio Carmani, if there is such a chap, must be rubbing his hands.

For the rest of us, it casts doubt on the sport's unspoken contract between the men who build the cars and the men who drive them, an understanding of implicit risk. And it might just mean the end of Formula One racing in Italy. But the lawyers will be able to retire after this one.

The technical analysis produced after more than a year's investigation into the possible causes of the accident that killed Ayrton Senna runs to 700 pages. It contains the detailed findings of scientists at Bologna University and the Italian aeronautical institute, guided by an ad hoc committee containing several distinguished figures.

What it apparently suggests is that a last-minute weld in the steering column of Senna's Williams-Renault broke while he was taking the Tamburello curve on the seventh lap of the 1994 San Marino Grand Prix, sending him into a concrete wall at 131 miles per hour.

But Frank Williams can afford the best lawyers in the world, and he will do everything he can to prevent the court reaching the conclusion that a careless piece of work by one of his employees led to the death of the most famous and beloved racing driver of his era.

Whether a trial can reach any sort of a satisfactory conclusion must be a matter for serious doubt. Thanks to the destruction of the car's black box recorder in the accident, most of the potentially relevant data is unavailable, and Senna's death has therefore been the subject of a great deal of speculation.

The proposed causes come in three types: the implausible, the possible, and the probable. In the first category comes the theory that the accident occurred as the result of an unforced error by the world's best driver on a corner presenting no challenge whatsoever.

The possible list includes the suggestion of a sudden instability caused by low tyre pressures. After an accident at the start of the race, the cars had been running behind the pace car and the rubber would have cooled, reducing the pressure significantly - temperature and pressure are critical to the performance of Formula One tyres.

The probable causes mostly revolve around tee car's steering. The steering column had certainly been modified, and it definitely snapped at some point, although it is hard to believe that metallurgists in Italy, or anywhere else, possess a machine capable of determining whether it broke before or during the impact with the wall.

The other rational suggestion concerns a possible failure of the car's power steering.

Actually, the longer all this goes on, the more seriously I begin to take the idea that the driver made a mistake. This was Senna's third grand prix with his new team, in the new Williams FW16B. He had spun out of the Brazilian Grand Prix and at Aida had gone no further than the first corner before being punted off by another driver. Senna was in a state of some anxiety.

But, as Frank Williams must know, you cannot advance this theory without incurring the wrath of the legions of Senna-worshippers. And it is the one theory that can never be proved.