Milwaukee launched the nation's first school-voucher program in 1990. Dozens of similar plans have since been proposed across the country to allow parents below a certain income level to choose to send their children to private or religious schools with tuition paid by the state.
The Supreme Court has not ruled on whether vouchers are constitutional. Lower courts have split on the issue. More tests will come. Legislation is either expected or pending in several states.
Voucher supporters say affluent people already have school choice. They can either send their children to private schools or buy homes in communities with good public schools. Poor people, meanwhile, are stuck with the local school where they can afford to live.
"We are in danger of becoming a two-tiered society -- one educated, skilled and rich, the other uneducated, unskilled and poor," says John Goodman, president of the National Center for Policy Analysis, a non-partisan institute which studies public-policy issues. "To avoid this, we must give parents at the bottom the same choices available to those at the top."
On the other hand, opponents say vouchers would further harm already failing public schools, that they benefit only a few poor students while leaving the rest behind, and that giving state funds even indirectly to religious schools violates the separation of church and state.
While parents have the right to send their children to religious schools if they so choose, it's unfair to ask taxpayers to fund religious organizations with which they disagree, says Barry Lynn, executive director of Americans United for Separation of Church and State.
"American taxpayers should never be forced to support religious indoctrination," Lynn says. "Giving public funds to sectarian schools is ultimately no different from forcing taxpayers to place their money in a collection plate."
Most recently the battle has moved to two fronts: Florida and Maine.
Florida became the first state to allow students statewide to attend private secular or religious schools with the aid of tax dollars -- up to $4,000 a year per student. The program was open to students in public schools that are deemed to be chronically failing by state testing standards.
Two schools in Pensacola were the first to qualify. However, on March 14, a Florida state judge declared the the Florida law unconstitutional. The fifty-three Pensacola students who were given vouchers will be allowed to finish the school year in private schools. Governor Jeb Bush plans to appeal the court's ruling.
Voucher supporters argue that competition with private schools will cause public schools to get better, not worse. They also say that in an increasingly secular society, parents ought to have the option of having their children educated in a more spiritual setting.
Opponents, however, say studies do not prove that students who receive vouchers perform better academically after they leave public schools. They also warn that religious schools that accept public funds through vouchers may open the door for government regulation of religious training.
"Bluntly, vouchers are not the Viagra of school reform; they're the snake oil," says Lynn.