The Use and Incorporation of Extralegal Insights in Private Law Reasoning

22 Pages Posted: 21 Oct 2013

See all articles by Ivo Giesen

Ivo Giesen

Utrecht Centre for Accountability and Liability Law; Utrecht University - School of Law

Date Written: October 02, 2013


Following the US example, European scholarship has seen more and more inter- or multi-disciplinary academic work being carried out relating to private law and civil procedure over the last few decades. In such studies ‘extralegal’ knowledge stemming from, for example, psychology, sociology and economics is combined with existing legal insights and arguments and transformed into ‘novel’ legal knowledge. This has often led to new thoughts on how to organize our legal landscape and to possible new public policy issues and solutions.

An intriguing question underlying these kinds of studies is whether it is in fact possible – and if so, how, why and when – to leap from such ‘extralegal’ insights to normative legal conclusions. How and when can any researcher step over from, for example, empirical psychological facts to legal normative value judgments (as one is required to do from a legal end, for instance as a judge ruling on a case)? What, if anything, allows anyone to do so? What is, in other words, the yardstick, or what are the conditions under which it would be safe to say that one could cross over from one side to the other? What kind of justification could there be?

By reviewing the existing methodological literature on this topic and by linking up with ideas about the (analogous) use of comparative law materials in other jurisdictions, this paper – methodological in nature – tries to come up with a workable ‘method’ for crossing the border between social science disciplines and the law. As it turns out, a due process approach is the best available option. This approach asks of judges, legislators and scholars to be or become familiar with the methodology of the social science at stake. That hurdle might be gigantic but might be overcome by using court-appointed experts to collect or at least evaluate the usefulness of the extralegal materials available. The judge would thus resort to an expert to advise him on how to be a decent gatekeeper when it comes to the possible use of (insights from) social sciences.

Keywords: Social Science and Law, Interdisciplinairity, Methodology, Due Process Approach, Private Law

JEL Classification: K10, K19, K30

Suggested Citation

Giesen, Ivo, The Use and Incorporation of Extralegal Insights in Private Law Reasoning (October 02, 2013). Available at SSRN: or

Ivo Giesen (Contact Author)

Utrecht Centre for Accountability and Liability Law ( email )

Janskerkhof 12
Utrecht, 3512 BL
0031302536148 (Phone)


Utrecht University - School of Law ( email )

3508 TC Utrecht

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