Consultation is crucial in all life-cycles of law and regulation. It potentially generates two positive outcomes. The first one is related to the widely recognized improvements in law and regulation, due to the enrichment of data and end-users positions collected. The second is that consultation could create conditions for an increased acceptance of final decisions and trust in public authorities. Public trust, in turn, supports compliance and reduces enforcement costs. Therefore, consultation should activate a virtuous circle of better law and regulation, acceptance, trust, compliance. However, mere consultation-based decision-making is not enough. Not only the process can result in being ineffective to activate the virtuous circle, but can also paradoxically backfire, leading to weak interests under-voiced, biased data collection, as well as crowding out motivation in taking part in future consultation. What makes consultation effective in activating the above-mentioned virtuous circle is the question the chapter deals with. It is organised as follows. Paragraph 2 investigates the main requirements that public authorities should take into consideration when designing and conducting a consultation process. They can be summed up in five criteria which can be considered the common core of the many consultation standard enacted around the world: accessibility of the process (paragraph 2.1), early stage consultation (paragraph 2.2), accessibility of the documents (paragraph 2.3), reasonable time to intervene (paragraph 2.4), feedback and justification of final rules (paragraph 2.5). A last point is about securing compliance already in the decision-making process and most specifically via consultation (paragraph 2.6). These minimum requirements will be critically reinterpreted and possibly enriched in the light of practical experiences and cognitive insights, both supported by literature stemming from various fields: law, economics, political science and psychology. The analysis will also show some of the many challenges decision-makers face in organising and leading a consultation, for instance, the frequent limited involvement of weak interests (as underlined in paragraph 2.1 and in the followings)
