In the context of the recent financial meltdown, the financial industry has frequently been accused of being indifferent to the irregular practices of its members or even to be criminogenic. But how do actors of the financial industry respond to such accusations and defend themselves? How do they justify their actions when facing legal charges as well as public blame? This article elucidates these questions through a rare ethnographic case: the first criminal trial of a trader involved in the manipulation of Libor, which took place in London in 2015. Tied to at least $300 trillion contracts, Libor is a benchmark that plays a key role in the financial industry. The paper offers a sociological framework to capture the justifications of financial wrongdoings, arguing that they are structured around three elements: (a) a conception of rules; (b) a narrative; (c) a form of responsibility. I distinguish three justifications: the one of the maker, of the interpreter and of the user. I finally discuss how these justifications contribute to the general tolerance towards white-collar crime.

The formulation of legal rules is a challenging issue for lawmakers. Tradeoffs are inevitable between providing more guidance by specific rules and enlarging the scope by general rules. Using real options theory we show that the degree of precision should be considered as a degree of flexibility which increases the value of the text. Thus, we derive a normative principle for a draftsman to choose between rules versus standards and to decide when the law should be enacted. In highly innovating environments, delaying the enactment allows lawmakers to obtain more information. Therefore, the lower the degree of precision of the law, the shorter the delay.