It is a generally held assumption that the EU economic free movement rights are tools in the creation of a European internal market; and that their main goal is the (negative) market integration of different national markets. Yet these freedoms do not determine how market integration is to proceed, or which kind of integrated European market will emerge. The resulting market may be more or less regulated, and the creation of the relevant regulatory rules may be allocated to a variety of sources. These options are reflected in the different proposed tests used to determine whether a national measure prima facie infringes one of the market freedoms. The proposed tests fall into two main categories—broad tests and narrow tests—and each type has its own implications for European integration. Broad tests, usually associated with obstacle tests or even with economic due process clauses, tend to be seen as having three main outcomes. One result of broad tests is centralization, implying that ultimate decisions concerning the legitimacy of national law rests with EU institutions, and particularly with the Court of Justice of the European Union (“the Court” or “CJEU”). Another outcome of broad tests is the possible harmonization of national laws through the European political process by increasing the amount of national legislation susceptible to being harmonized under Articles 114 to 118 on the Treaty on the Functioning of the European Union (“TFEU”). A third consequence of broad tests is deregulation through the elimination of national rules creating obstacles to trade. Alternatively, narrow approaches-usually associated with discrimination or typological tests-are usually coupled with regulatory pluralism via a greater degree of control of the harmonization competences of the EU, decentralization through the protection of a greater sphere of Member States' autonomy, and economic agnosticism. Views on the potential outcomes of broad and narrow tests are, in turn, related to normative debates about the ideal levels of centralization, harmonization, and regulation in the internal market.