The Da Costa ruling, however, determined that any ruling of the European Court of Justice must necessarily apply to all national courts when interpreting Community Law (Craig 2001). In this way, the law is guaranteed to be applied evenly in and in the same manner in all member nation courts when deciding Community Law issues, whereas prior to this ruling differing interpretations of the same facets of Community Law could be applied to the same issue.
It is important to note that this ruling does not affect the various national courts of the member nations of the European Union when interpreting national law, and in fact the European Union and its various courts, including the European Court of Justice, have no sway over such interpretations, as the European Union is not a true federal entity (Craig 2001). In this way, while ensuring the equitable interpretation of Community Law in all member nations and national courts, the ruling in the Da Costa case, as well as in subsequent cases, maintains the sovereign rights of the national courts when it comes to the interpretation of national or non-Community Law.
Application of Community Law in the United Kingdom
The use of Community Law by the courts in the United Kingdom and in the general practice and body of law in that nation is relatively straightforward, given some of the country's other interactions with the European Union and the general European Community. In 1972, the passage of the European Communities Act (which predates the establishment of the European Union, of course, but is still applicable -- just as the European Court of Justice was actually in existence and remained essentially unchanged since 1952) outlined the way that Community Law would be utilized and interpreted by the courts of the United Kingdom. Essentially, Community Law both present and future at the time that the Act was passed was determined to hold the status of true national law before UK courts, unlike foreign law, which could still be presented but only by a verified expert the interpretation of a specific body of foreign (e.g. French) law (Freestone & Davidson 1988).
This Act was and is also highly significant in that it deemed not only all rights listed explicitly in the terms of the various Community Treaties then in existences, but also any rights that had been or were to be developed under the terms of the treaty, effectively making any subsequent Community legislation also a matter of national law (Freestone & Davidson 1988). Not only that, but the Act contains provisions that provide for the direct enforcement of these rights within the United Kingdom, thus granting full executive, legislative, and ultimately judicial (through the European Community's courts interpretations of Community Law) power concerning Community Law and rights to the governmental offices and institutions established by the Community (Freestone & Davidson 1988). Even this is not where the powers granted to the Community bodies in the development and enforcement of law in the United Kingdom by the Act ended, however.
The United Kingdom made the power of the European Court's decisions and interpretations a matter of national law, establishing in the act that decisions regarding community law made by the national courts were to adhere to he principles established by the European Courts, and of referring cases to these European Courts whenever warranted and allowable according to the terms of the Community's judicial system (Freestone & Davidson 1988). Essentially, these combined elements of the European Communities Act means that Community Law will have the direct effect in the United Kingdom that the language and subsequent interpretation of the Community Law itself provides, unmitigated by further national legislation or jurisprudence (Freestone & Davidson 1988).
Craig, P. (2001). "The jurisdiction of the community courts reconsidered." In the European Court of justice, de Burca & Weiler, eds. New York: Oxford University Press.