In 1979, the Council of the European Communities declared its intention to ban battery cages for laying hens; one year later, everything about the ban is forgotten. During this preparatory year (1979-1980), all that happened is the publication of scientific reports, that is, attempts at producing knowledge as a basis for and justification of the ban decision. This paper aims at understanding to what extent ignorance and doubt were produced instead. By examining the reports, I demonstrate that there are three interrelated levels of ignorance production: (1) the missions given by the Commission to scientists were ambiguous, (2) questions inherent to animal welfare sciences, such as the significant variability of their measures and results, lead to a systematic standardization, and (3) the battery cage works as a techno-scientific promise and an “obligatory passage point” where scientists and industry meet. Disciplinary identity issues therefore lead scientists to adopt a double standard about the welfare of laying hens.