NPR's Nina Totenberg reports two major cases were argued before the Supreme Court today. The first case tests whether governments may offer vouchers to parents unhappy with public schools. The vouchers help pay students' tuition at private schools. Most participating schools are religious, so opponents say the plan is an unconstitutional subsidy for religion. The second case involves a death row inmate whose lawyers say he is retarded. The question is whether killing him would be cruel and unusual punishment.