New technologies generate risks, for the evaluation of which various mechanisms have been developed; the most frequent of these mechanisms consists of advice from committees of experts to the bodies whose role is to decide whether a new technology should be implemented or not. Such committees try to measure the magnitude of the threats that accompany the introduction of a new technology in order that the policy-makers may take their decisions in the light of the reports of the experts. The legitimacy of such reports is not only found in the technical capacity of its authors, but also in the impartiality of their recommendations. On numerous occasions, nevertheless, the effective presence of this evaluation finds itself today under suspicion. There are various methods that can be employed to try to resolve this problem. Firstly by reinforcing the mechanisms on which the technocratic evaluation of the risk are based; for example, through transparency in the selection of the experts. Secondly, by means of the incorporation of democratic mechanisms in the scientific-technological policy. The exposure of the internal conditions to the dynamics of the technological change that make possible the institutionalised involvement of society in the control of risk, as well as of the mechanisms to realise it are the principal subjects of this work