Stan J. Liebowitz, Willful Blindness: The Inefficient Reward Structure in Academic Research (February 21, 2013). Available at SSRN: http://ssrn.com/abstract=2214207:
The only reward structure that provides authors an incentive to choose the most efficient sized research teams is strict proration of author credit. Nevertheless, survey evidence indicates that the reward structure used in Economics for at least the last thirty years only incompletely prorates authorship credit, which should lead to inefficiently high levels of coauthorship. A possible reason for incomplete proration is the self-interest of economists with above average levels of coauthorship, a group disproportionately populated by senior economists and thus disproportionately influential. The well-documented increase in coauthorship over the last fifty years, both in economics and academia, may be better explained by the lack of proration than by any shift toward arcane technique or complex statistical analysis. Fictitious authorship, although of dubious ethical status, has the perverse impact of improving the efficiency of authorship when proration is incomplete. Grossly excessive coauthorship, which threatens to make a mockery of authorship itself in several other academic disciplines, may be the path down which Economics is headed if the reward structure is not altered.
This becomes relevant to law, especially because co-authorship is becoming more common as empirical scholarship becomes more common and as scholars who really belong in other disciplines (where co-authorship is routine) enter the law job market with their JD-PHDs.