In this paper, we expose the legal theories underlying two important classes of Legal Core Ontologies and show how these ontologies inherit both limitations and benefits (such as explanatory power) of their underlying theories. We do that with the help of a real case study in which we have normative omission and collision of principles. We use this case study to conduct an ontological analysis of the support for judicial decision-making in LKIF-Core (representing Kelsen’s Pure Theory of the Law) and UFO-L (representing Robert Alexy’s Theory of Constitutional Rights). We show that UFO-L is able to articulate the semantics of the content of judicial decisions by making explicit the individual’s legal positions that are raised in argumentation along a legal process. The same cannot be said of LKIF-Core that is based on the Kelsenian stance and focuses on the representation of general norms (norm types) and subsumption of facts to these norms.