Defining legal vagueness: a contradiction in terms?

Indeterminacy is an apparently unavoidable aspect of legal language and this paper aims to offer a taxonomical review of concepts related to linguistic and legal indeterminacy, with particular reference to the phenomenon of vagueness. Starting from the consideration that the notion of legal vagueness is itself intrinsically vague and extremely multifaceted, this study describes the main functions of vagueness and its connection with related phenomena such as ambiguity, contestability, and fuzziness. More specifically, the focus is on legislative texts, and illustrative examples are taken from the EU Directive 2011/92 on the assessment of the effects of certain public and private projects on the environment. Vagueness is here seen as an inherent feature of legal language rather than a threat to the rule of law. The paper illustrates the rationales behind different forms of legal and linguistic indeterminacy and, in particular, offers considerations on how vague choices may be exploited to shape normative texts.