Returns to unwanted education

In my inequality post, I wrote, somewhat speculatively,

The returns to education chosen and worked hard for are not necessarily replicated in education subsidized or forced.

Marginal Revolution points to a nice new paper by Pierre Mouganie making this point. From the abstract:

In 1997, the French government put into effect a law that permanently exempted young French male citizens born after Jan 1, 1979 from mandatory military service while still requiring those born before that cutoff date to serve. ... conscription eligibility induces a significant increase in years of education, which is consistent with conscription avoidance behavior. However, this increased education does not result in either an increase in graduation rates, or in employment and wages. Additional evidence shows conscription has no direct effect on earnings, suggesting that the returns to education induced by this policy was zero.