In 1856, the mayor of Brussels proposed the establishment of a municipal laboratory with a chemist to analyse food and beverages to restrain fraud. His proposal was accepted and a laboratory – possibly one of the first municipal laboratories in Europe – was set up. The laboratory still exists today. This paper aims at tracing the conditions in which it emerged, situating it within the laissez-faire context of the time. It was brought into existence by a liberal administration, in a period of little interventionism replete with unencumbered private interests (those of bakers, butchers, grocers, millers, pharmacists, doctors and so on). What will be considered here is the general mood with regard to food fraud, fair trade, correct price, and the quality of food in the first half of the nineteenth century. On a broader level, this contribution addresses the frictions between private and public initiative, while focusing on the process of construction of expertise. The paper makes use of contemporary documents such as reviews, newspapers, association reports and city council chronicles.