The use of foreign law to interpret the US Constitution is a complex subject that too often gets caught up in sound bites. Although at this point, the Supreme Court's use of foreign law in this way has been extremely limited, I have several concerns about proposals to increase that reliance. In this post, I'll just briefly mention one that hasn't gotten enough attention: the Court's lack of relevant expertise.

For a Supreme Court made up of generalists, even keeping up with all the US law that the Court has to deal with is a full-time job, one that the justices often fail at. But at least a justice addressing an issue of American law that he is unfamiliar with has the advantage of dealing with a body of law embedded in a broader legal system that he has at least some understanding of. By contrast, few if any justices have extensive knowledge of foreign legal systems. As a result, justices interpreting foreign law are likely to misunderstand the context of that law, and also to misunderstand relevant differences and similarities between the US and the foreign jurisdiction in question. Thus, even if it is theoretically possible for the Court to mine valuable insights from foreign law, it is unlikely that the real-world Court will actually be able to do so. This lack of expertise may help explain why those justices who do rely on foreign law never seem to do a systematic survey of the relevant foreign precedents, but instead simply pick a few examples that seem to support their position. To take an example from an area of law I'm familiar with, Justice Stephen Breyer sometimes relies on foreign law to justify his positions on federalism issues, as in his famous dissent in Printz v. United States. However, he has never confronted the fact that many federal systems in other democracies (e.g. - Germany) have fairly extensive judicial review of federalism issues, with judges using their power to limit the authority of the central government. Breyer, of course, has taken the position that the US judiciary should virtually never restrict federal government power on federalism grounds. Similarly justices such as Breyer and others who endorse the Court's abortion precedents routinely ignore the fact that most other nations impose more extensive constraints on abortion than would be permitted under US Supreme Court precedent.

These two examples are drawn from the work of liberal justices. However, I doubt that the conservative justices would be much better if they too started to rely on foreign law to buttress their positions in constitutional cases.