European standards are adopted by the CEN and CENELEC and remain voluntary.
Therefore, the manufacturer is free to apply relevant European standards or to fulfill
appropriate legal requirements by other means. However, the adherence to relevant
European standards brings an important advantage to the manufacturer: certification bodies and competent authorities are, in accordance with the directives, obliged to presume compliance with the directives, as far as the manufacturer has met the relevant requirements of the European standards (Article 5 AIMD MDD). Therefore, adherence to the relevant European standards provides a presumption of conformity with regard to legal requirements. Hundreds of European standards have been reviewed by CEN and CENELEC. The European Commission so far has published references of approximately 40 European standards in the official journal. Relevant standards that were published in the official journal have obtained a harmonized status and compliance with them creates the presumption of conformity.
The fulfillment of essential requirements and of requirements relating to the design and manufacture of medical devices must be established through the “conformity assessment procedures.” The manufacturer that places the medical devices on the market must conduct the conformity assessment procedure in accordance with the directives. By affixing a CE mark to each medical device, manufacturers confirm that they have met all requirements of the directive and that they have correctly followed conformity-assessment procedures. The details of conformity assessment procedures were adopted in 1990 and reconfirmed in 1993 by the Council of Ministers, who established eight typical procedural modules for conducting conformity assessment. These modules have been used in different EC directives governing machinery, personal protective equipment, telecommunication equipment, and pressure vessels. The use of conformity-assessment modules allows for a graduated approach to determine how much an independent certification body should intervene in a conformity assessment procedure. According to the MDD, medical devices are classified in relation to the potential hazards associated with their use. Depending on the class assigned to each device, the corresponding conformity-assessment module(s) vary