This thesis is about a particular kind of European Union legislation known as the ‘optional instrument’. The thesis examines and discusses existing and proposed EU Optional Instruments (OIs) in different fields of European law, including company law, intellectual property law and procedural law (such as the European Company, the Community Trade Mark and the European Small Claims Procedure, respectively), as well as contract law.

In general terms, the principal aims of this research are fourfold. First and foremost, the thesis aims to identify the core elements that define this kind of EU legislation, and that distinguish it from other kinds of EU legislation, notably ‘harmonization’. The second main objective is then to describe in detail and ultimately ‘map’ a number of EU OIs that have been adopted or proposed in the various EU policy areas mentioned above, charting their development, characteristics and (where appropriate) usage in practice. Thirdly, the thesis seeks to assess and evaluate EU OIs by investigating the advantages and disadvantages of creating optional private law instruments at European level as an alternative to harmonization. And, last but not least, the research aims to explain the apparently varied degree of ‘success’ of EU OIs already in existence, by identifying and analysing possible factors that could play a role in this respect.

While there does already exist considerable literature on optional instruments as a distinct form of legislation in specific areas of European law, a general account of Optional Instruments as a distinct kind of EU legislative method that transcends individual policy areas is much harder to come by, and to date no research project has conducted an in-depth theoretical study of the nature, object, advantages, drawbacks and usage of EU OIs. Such a study is therefore needed in order to build upon the existing academic research into this fast-evolving phenomenon.

Chapter 2 concerns the question of what defines EU Optional Instruments. More specifically, it is focused primarily on identifying the grounds or core elements on the basis of which the various legislative measures under examination in this study can be classified as EU OIs. In addition, this chapter seeks to place EU OIs in the wider context of optional instruments in general, as well as contrasting EU OIs with other kinds of EU legislation, and particularly EU ‘approximation’, both in a conceptual and in a technical, legal sense.