Slovenian npm's 10th anniversary conference report in Paris on 7 and 8 September 2017 in the framework of the European NPM Forum; a presentation was given of the main conclusions from that meeting and a written summary made available in English and French. Reference was also made to a concept paper on measuring the impact of NPMs which had been prepared by the European Training and Research Centre in Graz for consideration at the Paris meeting. At the outset, it was acknowledged that the NPMs represented at the conference varied significantly in terms of size, legal structure, means and - above all - age. Any institution which has reached the 10 year milestone, such as the Slovenian NPM, is likely to feel the need to review its functioning, take stock of what has been achieved and seek possible new paths of action. In contrast, a relatively new mechanism will naturally be more focussed on establishing itself and developing its activities. Consequently, the conclusions reached would no doubt be of varying degrees of relevance for the different participants. But they should certainly provide food for thought for everyone present; indeed, any NPM had an interest in maintaining a critical eye on its performance at every stage of its existence. The discussions at the conference were organised around four distinct - albeit far from watertight themes: 1. Reasons for assessing the impact of an NPM, who should do the assessment and when should it be done? 2. What is NPM impact (criteria)? 3. How to measure impact (indicators: data needed, facts or perception,etc)? 4. How to establish a link of causality between changes observed and an NPM’s work? Each of these themes was considered in turn by two working groups meeting in parallel, followed by discussion of the working groups’ conclusions in plenary session. As from the very beginning of their discussions, participants wrestled with the concept of «impact» as compared to that of «effectiveness». The general tendency was to consider that attempts to assess the impact of an NPM inevitably involved evaluating the mechanism’s mandate, resources and working methods. This was reflected in the conclusions reached under the different themes. Theme 1: Assessing NPM impact: why, by whom and when? Reasons for assessing impact Participants considered that it was perfectly normal practice to review - at the appropriate time whether a body entrusted with a particular task was achieving the goals/objectives which had been set. And this was all the more necessary when the body concerned - such as a national preventive mechanism - was financed by public funds. However, it was recognised that assessing the impact of an NPM was complicated by the nature of the overall objective i.e. prevention of torture and other forms of serious ill-treatment. The extent to which an objective of prevention was being met did not lend itself easily to evaluation. The assessment process should certainly test whether the «internal performance» of the NPM was capable of having a preventive effect. This could identify and establish good practice and - if necessary - trigger a rethinking of strategies, specific objectives and working methods. It might also lead to a reinforcement of the means placed at the mechanism’s disposal (staff, etc) if they were found to be inadequate. More generally, if carried out in the right spirit, assessment should be a source of motivation for the persons working for the NPM and could boost their self-confidence. Assessment could reveal whether recommendations made by the NPM were being fully implemented by the national authorities and whether the changes involved - to practices, standards and laws - were having the desired effect i.e. improving in concrete terms the protection of persons deprived of their liberty. It could also fuel public debate about issues related to the prevention of ill-treatment and, more specifically, provide answers for the media and general public about what the mechanism has achieved. If it was demonstrated that the NPM was having an impact, this would increase the mechanism’s credibility vis-à-vis the national authorities, its interlocutors in places visited and the public at large. And such a positive assessment could be used to justify the maintenance of - and even an increase in the NPM’s resources. IMPLEMENTATION OF THE DUTIES AND POWERS OF THE NPM IN 2018 NATIONAL PREVENTIVE MECHANISM UNDER THE OPTIONAL PROTOCOL TO THE UN CONVENTION AGAINST TORTURE AND OTHER CRUEL, INHUMAN OR DEGRADING TREATMENT OR PUNISHMENT 51