Over at The American Prospect, Dana Goldstein takes on school voucher programs, writing:
Voucher programs stack the deck against families who prefer a secular education for their children. In Milwaukee, the site of the largest private-voucher experiment to date, 102 of 120 participating schools are religious-affiliated.
I'm not really sure how this follows. Vouchers wouldn't actually prohibit anyone from attending a secular school, and, in fact, would actually expand the number of secular schools available for many students. Without vouchers in place, students and their parents are typically required to attend a single, particular public school. Depending on how the system works, they may have a few options, but even that's somewhat rare. Vouchers, of course, give students and families more choices. Even in a program dominated by religious schools like Milwaukee, participating students would still be able to go to the secular public school they would've otherwise attended, plus would have 18 additional secular schools from which to choose from. How, exactly, this is "stacking the deck" beats me.