Browsing the last 40 years of the European Journal of Political Research (don’t ask why!) I noticed this bit about political scientists, jurists, and constitution.  I’ve tried to make the same point here before but Maurice Duverger (1980) does it far more elegantly than I have:

It is not usual for political scientists to construct analytical models defined initially by constitutions. However, no-one would dream of  watching a game of football or of bridge without taking into account the rules of the game. They constitute a fundamental aspect of the players’ strategy and tactics, the framework of which they define.  Jurists have obscured this deep nature of constitutions by considering them as sacred texts, capable of only one interpretation, which would be “true”, while the others were “false”. What I mean of course is that each commentator believes his interpretation – which differs from that of his colleagues ~ to be the only true one. In actual fact, the interpretation of a constitution cannot be separated from the interrelationship of political forces to which it is applied. If the interrelationship varies, the structure and functioning of the form of government established by the constitution vary at the same time. 

One implication of Duverger’s claims that is relevant in the context of writing a new constitution is that the effects of institutions vary with the political forces that operate within it – but the institutions themselves, perhaps especially the electoral system, affect the `political forces’.  As far as I can tell there has been very little consideration of these issues in the debate over the new constitution – including in the constitutional council – in large part because the authors of the proposals share the naive view that constitutions have one correct interpretation rather than setting the basic rules of the game that the political actors will try to manipulate to their advantage.

Duverger, Maurice (1980). “A New Political System Model: Semi-Presidential Government” European Journal of Political Research  8: 165-187.