The trial is limited to doping in cycling, even though athletes in other sports were also reportedly implicated in the discovery of blood bags and other doping equipment in 2006.
Santamaria can rule only on matters covered by Spanish law as it applied in May 2006, when police raids uncovered a mass of blood doping evidence in labs, offices and apartments.
The World Anti-Doping Agency wants all evidence to be released.
Also on trial are Fuentes’ sister and fellow doctor, Yolanda; Manolo Saiz, a former ONCE and Liberty Seguros team sports director; and Vicente Belda and Ignacio Labarta, both associated with the former Kelme team.
Jose Luis Merino, another doctor, was due to be tried, but Santamaria granted him a temporary stay last week after he presented medical reports saying that he is suffering from Alzheimer’s disease.