Are Human Rights Treaties the Inspiration for National Constitutions?

“It is widely thought that the rapid growth of the international human rights regime has profoundly influenced the practice of written constitutionalism at the national level,” writes David Law and Mila Versteeg in their brilliant article recently published in the NYU Law Review.

But is there empirical support for such an assumption? Much to my surprise, their answer is a resounding no. After an exhaustive empirical analysis comparing national constitutions with international and regional human rights treaties, they conclude that “our analysis uncovers no clear evidence that transnational human rights instruments are shaping global or even regional trends in constitution writing.” With regard to the canonical international human rights instruments (UDHR, ICCPR, ICESCR), they find that:

The results of the regressions offer little or no support for … for the notion that any of the three leading international human rights instruments have been widely emulated by constitution makers. Instead, they suggest only that different types of countries tend to exhibit constitutional similarity to different treaties.

Here’s their longitudinal analysis of the relationship between those instruments and national constitutions.

From this they make a curious argument about the ICCPR:

From the position of the vertical line [at year 1966], it is clear that the growing similarity of the average constitution to the ICCPR predates the introduction of the ICCPR: The average constitution had already started to resemble the ICCPR before the ICCPR came into existence. Obviously, the ICCPR could not have been shaping global constitutionalism before it even existed. A more logical interpretation of this chronology is, instead, that the ICCPR merely happened to reflect or express global constitutional trends that were already underway.

They make a similar argument with respect to the ICESCR:

Whether a country has actually ratified the ICESCR … is not a meaningful predictor of whether its constitution resembles the ICESCR…. [T]here was no statistically significant increase in constitutional similarity to the ICESCR following its adoption in 1966, which casts doubt upon the notion that it has served as a model for constitution writers.

Based on my knowledge of the drafting history of both of these treaties, I’m not convinced by their conclusions. Can one say with confidence that the ICCPR and the ICESCR obviously did not shape global constitutionalism prior to 1966? It is well known that both treaties had incredibly long drafting histories, with U.N. General Assembly directing the drafting of the treaties in 1952 and the drafting committee completing its work in 1954. Cold War politics delayed the ultimate adoption of the ICCPR and the ICESCR treaties until 1966, but that doesn’t mean that the draft texts were not influencing global constitutionalism prior to that date.

As newly-independent nations were looking for inspiration in the drafting of their new constitutions, it is quite plausible that countries within the Western European sphere of influence would be inspired by the negative rights expressed in the draft ICCPR, just as countries within the Soviet orbit would be inspired by the economic and social rights expressed in the draft ICESCR. The politics of the day may have delayed the adoption of these treaties, but their influence could easily have predated their adoption. So the sharp uptick prior to 1966 in the correlation for both the ICCPR and the ICESCR makes perfect sense to me. It is likely the result of newly-independent nations from both camps drawing inspiration from the ICCPR and ICESCR draft human rights treaties.

Of course, this point is one small aspect of a monumentally useful article. I highly recommend it to you. It offers a fascinating analysis of the sources of inspiration for global constitutionalism.