Article R2146-1 of the French Labour Code
Any director or manager of a trade union or union of trade unions who, in disregard of the provisions of the first paragraph of article L. 2131-2, opposes the free formation of a trade union or professional association of persons exercising the same profession, similar or related professions, contributing to the establishment of specific products or the same liberal profession, is punishable by a fifth-class fine.