The development of a uniform European trade mark law regime has taken so many different paths over the past decades that the state of the law is now more or less incomprehensible to everyone. The regime is primarily shaped by judicial creativity, and the Court of Justice of the European Union (CJEU, earlier the European Court of Justice, ECJ), has not even hesitated to set aside the letter of supranational statutes of central importance. The CJEU has explained this shift in power to make law, from the legislature to the court, simply by the need to interpret the legislation not solely on the basis of its wording, but also in light of the overall scheme and objectives of the system of which it is part. Besides the question of a democratic deficit, permeating the overall European unification process, the inconsistent application of trade mark statutes is disquieting. On one day, rights can be invoked to prevent registration of a trade mark only if use of that mark is likely to cause a change in the economic behaviour of purchasers. On another day, free riding on the reputation represented by the trade mark is an actionable infringement of the rights per se, in spite of the need for correlation between the rights to prevent registration and to prevent use of signs or expression in the course of trade. The position of the CJEU, that the application of the legislation depends on the circumstances in each case, is highly agreed upon. But it brings the question to the fore of what the yardstick is for deciding one way or another based on the circumstances in the case? More to the point, what is the normative basis for the uniform trade mark law regime, justifying that even statutory law is set aside? This study investigates the rationale for trade mark based rights to limit the freedom of others to use whatever signs or expressions they like in the course of trade. The investigation starts from a positive analysis of the reasons for trade mark rights, but also aims at providing a basis for what ought to be the guiding star when shaping the uniform regime. Even if fairly consistent assumptions often transpire from the case law handed down by the CJEU, the rulings remain difficult to reconcile at best and are unconvincing at worst, as long as the Court refrains from rendering any implicit logics for the decisions explicit. The absence of a clear theoretical basis for the trade mark rights has very practical implications. Not only does the (maybe apparent) conflict with the rule of law result in high social costs in terms of legal uncertainty. It may also affect the will to transpose i.e. the rulings of the CJEU into the trade mark laws applicable in the States participating in the European unification process.