Ganesh Sitaraman (Harvard Law) has posted 'The Use and Abuse of Foreign Law in Constitutional Interpretation' on SSRN (Harvard J of Law and Public Policy, forthcoming). This is the abstract:
This article provides a typology of the uses of foreign law in order to provide insight into whether foreign law can be appropriately used in constitutional interpretation, when, and what the stakes and parameters are in each case. Much of the commentary on foreign law usage has focused on the justifications for using foreign law and the principled or practical arguments against using foreign law. But the focus on the why of foreign law has obscured a more basic question - the ways in which foreign law can be used, that is, the how of foreign law. Focusing on the why of foreign law threatens to generalize arguments into debates on foreign law when it may be more helpful to debate particular methods of foreign law usage. Some methods of use may be more easily justified and others totally unjustifiable. Some scholars have recognized the need to focus on the how of foreign law, but they have identified only a limited set of ways in which foreign law could be used. This limited categorization of foreign law usage prevents clear evaluation of which uses are appropriate. The article's typology demonstrates that most uses of foreign law are not problematic, and as a result, that the foreign law debate should focus specifically on the few uses that are potentially problematic, rather than on foreign law more generally.
As the author himself says: "these days, everyone has something to say about the use of foreign law in constitutional interpretation". Much of the relevant American literature is dominated by the US perspective to such an extent that the main lines of argument are often difficult to follow for outsiders (like myself). Sitamaran's paper, too, is focussed on the US, but his views do have a broader application. And whether you agree with his typology or not, the emphasis on the 'how' question of the use of foreign materials is certainly very welcome.