Abstract Chapter III, first, defines subjective substitutive direct effect as it takes shape in Van Gend & Loos and the doctrine stemming from it. In doing so, special attention is devoted to the conferral of rights and the substitution effects stemming from the duty of disapplication as the key elements of such manifestation of direct effect, in the light of the two principles of effectiveness and effective judicial protection. It then identifies the jurisprudential milestones related to a notion as chameleon-like and iridescent as direct effect. Amongst these lies the test on direct effect, whose uncertain functioning is explored, as well as its dubious relevance in the conceptualization and practice of direct effect, today. In particular, the ambit and potential of unconditionality are examined, and so is the merging of direct effect with direct applicability, in concreto. The focus is also on the implications deriving from a selective disapplication of national law conflicting with EU primary and/or secondary law, taking the principle of proportionality of penalties as the privileged tool of investigation.