The term “ad-hoc legislation“ is often used in the media and in legal literature to label laws as deficient or even “unlawful” as such. From a legal point of view, it is primarily the constitution which provides regulations for the legislature: Therefore, the aim of this diploma thesis is to examine the constitutional limits of ad-hoc legislation in Austria. As “ad-hoc legislation” is not a legal term, the first objective of this diploma thesis is to obtain a definition of for this term, at least valid for the thesis. This will be followed by an analysis of the constitutionality of ad-hoc laws in three parts: The first part deals with the various elements of legislative procedure on the federal level by investigating peculiarities and inadequacies of ad-hoc legislation and analyzing their constitutional consequences. The second part considers potential shortcomings in the phrasing of ad-hoc laws and their constitutional implications. The third part investigates ad-hoc legislation in the light of the principle of equality. This comprises an analysis which examines potential systematic and content-related deficiencies of ad-hoc legislation. On the basis of this analysis, it is ultimately possible to determine which circumstances surrounding ad-hoc legislation, including its legislative procedure on the federal level and its formal as well as content-related peculiarities, can lead to its unconstitutionality.