Key to concerns about public involvement in technology governance is the concept of lay expertise, the idea that lay people possess some kind of special knowledge that neither trained experts in technology, ethics and social sciences nor professional politicians possess. There are at least four different meanings of "lay expert": (1) Lay people who are educated into quasi-experts on a particular issue or technology; (2) Lay people who turn themselves into experts in order to challenge scientific experts; (3) Lay people with particular knowledge based on tradition and experience; (4) Lay people who represent an alternative perspective to expert views because they are non-experts. The challenge is that lay people are often ignorant in the relevant matters and wish to leave governance to experts. Still, there are normative reasons for lay engagement, either as stakeholders or as citizens in a deliberative democracy. According to the second approach, political decisions should be based on an inclusive open debate aimed at the better argument, providing lay people a crucial role in governance. In order to include lay people without making them hostage to experts, politicians or interest groups, we can engage them in focus group interviews which are analysed by social scientists and included in the interdisciplinary debate in journals and political forums.