Festina's masseur Willy Voet was stopped on the Franco-Belgian border on his way to the race in possession of hundreds of bottles of doping products, triggering a massive investigation that almost caused the Tour to be abandoned.
The trial, which has 10 defendants, is the culmination of two years of accusations and counter-accusations in France over drug-taking among professional cyclists.
The defendants are charged with various offences connected with encouraging and facilitating the use of illegal drugs in sporting competitions.
Most of the defendants face jail terms if found guilty.
The scandal has become known as the `Festina Affair' in reference to the Andorran-registered watchmaking company which sponsored the Franco-Spanish team taking part in the Tour de France race two years ago when the scandal broke.
Festina's masseur Willy Voet was stopped on the Franco-Belgian border on his
way to the race in possession of hundreds of bottles of doping products,
triggering a massive investigation that almost caused the Tour to be abandoned.
Virenque, five times the winner of the King of the Mountains climbing title at the Tour de France, said he had never knowingly taken doping products nor incited team-mates to do so.
"I put my confidence in my doctor - all I wanted was not to fall ill and not turn in a positive test later," he explained in the witness stand.
Asked if he had received injections Virenque said: "Yes. But it was just vitamins and supplements."