The opacity of law: on the hidden impact of experts' opinion on legal decision-making

It is well known that experts’ opinion and testimony take on a decisive weight in judicial fact-finding, raising issues and perplexities that have long been under scholarly scrutiny. In this paper I argue that expert’s opinions have a much wider impact on legal decision-making. In particular, they may generate a problem that I will call ‘the opacity of law’. A legal text, such as a statute or regulation, becomes opaque if a legal authority is not able to grasp its full linguistic content but is nevertheless in a position to use it, thanks to an expert’ opinion, in legal decision-making. When this occurs, not only do experts contribute to factfinding but also to determining the content of the law. In the paper I analyse the linguistic and cognitive sources of this phenomenon, its characteristics and troublesome consequences, and the different kinds of opacity that may affect legal decision-making.