* This paper is to be published in
G. de Burca and J. Scott (eds), The Changing Constitution of the EU:: From
Uniformity to Flexibility (Hart Publishing, 2000). The book grew out of a
seminar at the European University Institute in Florence organised by the
editors. I would like to convey my appreciation to audiences at Pace
University, New York and King's College, London, as well as to the participants
in the Florence seminar, for their verbal and written comments on earlier
versions of this paper. The usual disclaimer applies.