This paper presents a non-preference-based approach to the analysis of negative freedom. It is argued that a proper understanding of (different conceptions of) negative freedom necessitates an examination of the consequences of changes in the set of feasible alternatives. For this reason the paper does not focus on freedom rankings of opportunity sets but on freedom rankings of opportunity situations, i.e., pairs consisting of a feasible set and an opportunity set. Three different freedom rankings of opportunity situations are axiomatically characterised. (...) Each of the three rankings forms a generalisation of the purely cardinality-based freedom ranking of opportunity sets presented by Pattanaik and Xu (1990). (shrink)