The article analyzes the individual communications of the UN Human Rights Committee on how the latter conceptualizes equality under the ICCPR. It finds an implicit taxonomy in the case law that is not reflected in the doctrinal formulae that the HRC applies. The argument proceeds in several steps: First, I argue that the concept equality in human rights treaties depends heavily on its operationalization by courts and quasi-judicial bodies, like the HRC. Second, I analyze the doctrinal formulae that the HRC has developed in order to specify equality. I argue that the case law is rather inconsistent and does not give significant guidance for resolving actual cases. Third, I present the results of a systematic analysis of the case law of the HRC. The latter shows a rather stable pattern which is not reflected in the doctrinal formulae: The best predictor whether the HRC finds a violation of Art. 26 ICCPR or another equality norm of the Convention is the existence of a suspect criterion on which the challenged distinction was based. There are only very few cases in which a violation is found in the absence of a suspect criterion. The majority of these cases arguably concerned arbitrary state actions. At the same time, the HRC has only rarely held that a state has not violated an equality norm despite the existence of a suspect criterion.