The proceedings instituted against three European patents held by the US company Myriad Genetics, on the BRCA1 gene and the breast cancer diagnosis gene, resulted in the total or partial revocation of these patents. These decisions put an end to the legal monopoly claimed by Myriad Genetics on the BRCA1 gene and on breast cancer gene tests, and left the field open to European geneticists to develop and implement their test methods within the framework of a clinical not-for-profit organization. The opposition procedure, through which any actor is allowed to challenge European patents, was used by geneticists doctors in Europe to refuse the emergence of an industrial monopoly on a medical service offered in a clinical context. The decision to revoke or strongly limit these patents was based on the European Patent Office's refusal to establish an invention priority on a sequence that had errors at the time the application was filed by the patent holder, in September 1994. The patent holder was granted an invention priority only on 24 March 1995, when it filed an application for a corrected sequence of the gene. But by then the BRCA1 gene sequence had already been divulged in a public data base, Genbank, from October 1994, notably by Myriad. Myriad Genetics' patents were thus victims of the patent race that prompted the firm to file multiple patent applications on insufficiently validated sequences, and of the conflict between diffusion in the public domain and the novelty requirement. Opposition to the patents, undertaken by a coalition of medical institutions, human genetic societies, two States, Holland and Austria, an environmental protection organization (Greenpeace), and the Swiss Labour Party, made it possible to preserve and develop the clinical economy of genetic tests in Europe. It resulted in amendments to intellectual property laws in France and thus extended the possibility of using compulsory licences for public health purposes to in vitro diagnosis.