In the aftermath of Marks & Spencer, the „need to safeguard the allocation of the power to impose taxes between the Member States“ has evolved as a complex concept of possible justification for discriminatory or restrictive tax rules. Even though it has since been discussed in every major case which scrutinized national tax legislation as to its compatibility with EC fundamental freedoms, the significance and limits of this concept remain vague. A closer look at the relevant case law reveals that the desire to preserve the allocation of tax jurisdiction does not amount to a well-defined justification of its own but rather serves as a generic term for a heterogeneous set of legitimate reasons of public interest. Most of these different aspects of tax equity or inter-nations’ equity can indeed be integrated into the already existing justifications for discriminatory tax measures; some also fill a gap created by the deformation of the notion of fiscal cohesion in the jurisprudence of the ECJ. Ultimately, the future importance of the „allocation of the power to impose taxes“ will to a large extent depend on the evolution of the court’s case law on proportionality requirements.