Öz In the former candidate countries, the decisions of Association Councils have been construed as a kind of treaty. In most cases, they have been either promulgated by a governmental decree or published in official gazettes. All the same, the decisions of the EC-Turkey Association Council, established by the Ankara Agreement of 1963, are not generally viewed as a treaty i.e. agreement or memorandunı of understanding . Neither is it counted on as an act of government so as to subject to judicial review. No concrete answer has been giyen hitherto to the question as to the legal status of the Association Council decisions in Turkey. In the midst of uncertainties, this article endeavours to look at the legal nature of Association Council decisions per se and the 1195 Association Council Decision in particular. The 1195 Decision establishing a customs union between EC and Turkey was neither approved of by Parliament nor ratified by President. Corollary, it was not published in the Official Gazette. This article argues that the 1/95 Customs Union Decision should have been put into force by way of the procedure laid down in Article 90 of the Turkish Constitution. As having not been done as such, - the author opines that - it is an unconstitutional document which must be declared as null and void. This article casts light on the case law of the Council of State and the Constitutional Court to see if there is any likelihood that the 1/95 Decision be declared by the said Courts as having no legal validity in domestic law.