Why some countries incorporate language from international treaties into their constitutions and why others not do so are among the most important questions in international law as well as the focus of Mila Versteeg's (2015) thought-provoking article "Law versus Norms: The Impact of Human-Rights Treaties on National Bills of Rights." Versteeg's data, among the most original and important in this field, lead people to think that treaties affect both norms and laws, which in turn affect constitutional language development. Building from Versteeg's work, the author advocates that scholars ought to think carefully about the complicated counterfactuals and causal processes behind the process of constitutional language change and to engage further the observational implications of the explanation in terms of norms versus those in terms of institutions. Thinking more carefully about the causal pathways, as well as the appropriate counterfactuals, could open up important avenues for exploring possible mechanisms for domestic constitutions to be affected by international treaties.
Sen, Maya. "How Ratifying Treaty Rights Could Affect Norms, Laws, and Constitutional Language." Journal of International and Theoretical Economics 171.1 (March 2015): 112-117.