Chapter 5 analyzes acquisitive prescription, a broader concept than adverse possession, and argues that registration-based acquisitive prescription with title and good-faith requirements can be justified by efficiency under certain conditions—Possession, however, is redundant, and may even give rise to undesirable outcomes. Given that boundary disputes can be left for another doctrine, possession-based acquisitive prescription—no matter whether possessors act in good or bad faith—can hardly be justified on an economic basis in countries with well-functioning registrars if possessors do not have title. The possession-based acquisitive prescription can only be justified in jurisdictions with dysfunctional registrars.

In this chapter, I move on to resulting normative questions about the culpability principle, causal contribution, and command responsibility. I engage in deontic analysis of what type of contribution the culpability principle actually requires, and whether the requirement might be reconceived.

First, I will examine why criminal law requires causal contribution, and the degree of contribution required. I will argue that the requirement in relation to accessories is not onerous; ‘risk aggravation’ satisfies the culpability principle.

Second, I consider ambitious proposals to re-imagine culpability, i.e. to develop a new deontic account that does not require any causal contribution. A theme of this book is that ICL can present us with new questions that can lead us to adjust our basic assumptions from criminal law theory. On this issue, however, although the arguments are intriguing, my conclusion is that on a coherentist all-things-considered judgement, they are as yet far too tentative and undeveloped to provide a convincing basis for criminal sanctions. Accordingly, the current best theory is that accessories must at least elevate the risk of the crimes occurring.