Norm Ornstein has this oped in the NY Times. You can find my analysis of mandatory voting and its possible adoption in the US in Voting Without Law?, 44 University of Pennsylvania Law Review 2135 (1996). It is hard to see the solution adopted here as a way of dealing with low turnout primaries, as Norm suggests. In places like Australia, there are many fewer elections subject to the mandatory voting rules. See also Bob Bauer’s comments.