Yes, says Mark Tushnet, in this interesting essay, and see his Opinio Juris posts here and here. By globalization of constitutional law, he means "convergence among national constitutional systems in their structures and in their protection of fundamental human rights" but short of uniformity and with no claims about the rate of convergence (could take one year or one thousand years). I find this idea much more puzzling than Tushnet or his commentators do. Consider --
1. The argument resembles the "end of history" argument made famous by Francis Fukuyama. Fukuyama argued that the collapse of communist systems from 1989 to 1991 made clear the (eventual…) ultimate domination of liberal market-based democracy around the world. Fukuyama's argument looks less good today, what with the rise and rise of authoritarian China, the recovery of authoritarian Russia, the spread of Islamist thought, and the resurgence of socialism or whatever it is in places like Venezuela. But this is the question: is Tushnet's thesis just a version of Fukuyama, or is he saying something different?
2. Fukuyama had a specific mechanism in mind: he argued that technology develops unidirectionally. The ancient Greeks were wrong to think that history moves in cycles; history moves in a straight line because of the accumulation of knowledge. The connection between technological advance and liberal democracy was the weak link in his argument; technology serves China very well. Does Tushnet adopt this mechanism or does he have something else in mind?
3. Tushnet does discuss mechanisms, different ones. One is the idea that judges meet each other at Alpine conferences and exchange ideas. Why judges? Judges played no role in the collapse of communism, which was the key moment for modern convergence. Nor did they play a role in the collapse of authoritarian systems in the 1970s, or for that matter in the collapse of fascism. Why should we think they play an important role in constitutional convergence in general? In our country, of course, they change the constitution on what seems like a day-to-day basis. But outside crazy United States, the main agents for constitutional change are not judges but legislatures. Well, of course, legislators meet their counterparts in the Alps and elsewhere, and no doubt exchange ideas. Suddenly, this idea of people influencing each other gets less exciting. Government officials and others have always met with each other and paid attention to what is going on in other countries, and often self-consciously imitated what is going on in other countries. Think of the Japanese during the Meiji Restoration sending out delegations to learn what works and what doesn't work in the west. Is Tushnet's claim that constitutions have been converging since the beginning of the state system? Or that it is a post World War II (or post cold war) phenomenon? What has changed exactly?
4. Tushnet discusses another mechanism. States compete for capital. Investors will send capital to states with better institutions, all else equal. Thus, states have an incentive to improve their institutions toward some optimum; hence, convergence. But must there be only one optimal set of institutions? Perhaps, there are multiple equally good sets of institutions. How do we know?
5. So states have been imitating each other for centuries, and they have also competed for capital and migrants and trade and resources and much else. So if Tushnet's mechanisms are accurate, we should have observed convergence taking place long ago, with one state stumbling upon whatever works best through experimentation and then other states copying the first state. And yet—states seem to be getting different all the time. Surely, there was divergence from, say, 1900 to 1930. And are we so sure that divergence is not occurring even today? Consider the way that European countries have modified their constitutions so as to yield authority to European institutions. This activity has perhaps caused European constitutions to converge, but to diverge with respect to non-European constitutions, which do no such thing.
6. Convergence then seems like such an obvious phenomenon; the puzzle is why states didn't converge long ago, and why they often seem to diverge. What accounts for the rise of socialism, and all the constitutional changes it wrought? What accounts for the rise of Islamist thought—witness the constitutional changes it brought to Iran. These are big questions that swallow up the constitutional convergence thesis. Even as states imitate each other and compete for capital and converge, people living in those states are saying, "We don't like this one bit!" They conduct a coup or a revolution or some such thing, put into place a new model that others like, and divergence is on its way. Does Tushnet really think that this can no longer happen? And that is why constitutional convergence is now (or has always been?) inevitable?