I think the "Ban the Burqua" controversy is basically a conflict between two principles of ethics-the deontological (based on issues of justice) and the utilitarian (based on issues of happiness.) Deontological arguments of this sort are often used by people on the libertarian right--"No matter how unbalanced the distribution of wealth, the Government must never interfere with property rights". Nussbaum's NYTimes argument against Burqua bans has a similar form-- "No matter how many women are made miserable by the burqua, we must never interfere with religious freedom." Some of us use the utilitarian argument that banning the burqua could help to bring some Muslim women in greater contact with people outside their orthodox families, and thus give them more freedom of choice in the long run. This seems to be a more important fact than the abstract principle defended by Ms. Nussbaum. This issue is confused by the fact that the primary motivation for most burqua banners is Islamophobia. ( like the banning of Minarets.) Nevertheless, some people do the right thing for the wrong reason.
Utilitarian arguments do require more empirical input than justice arguments. Will the ban really give women more freedom, or just prompt their husbands and fathers to keep them permanently at home? Can this problem by more effectively dealt with by having the burqua wearers be persuaded by their hijabi and bare-headed sisters? Can the law really be written so that it doesn't ban ski masks? I'm still uncertain about the answers to these questions, but I do think these kinds of issues need to be considered, rather than only thinking about justice in the abstract. Abstract principles of justice often produce concrete examples of injustice.