That kind of evolution is likely to mark the life of this misbegotten law, which undercuts public education by initiating the country's first universal voucher program to funnel taxpayer money to private schools.

Some legislators who were rightly unhappy with the successful voucher bill supported amendments to require background checks on private-school teachers, double the funds for the State Office of Education to administer the law and shorten the time before the first evaluation from seven years to five. They're hoping the amendments will soften the law's impact. We wish that were true, but the fact is, no one knows with any degree of certainty just what this law will do.

Money to support the program will come from General Fund taxes, not from the Uniform School Fund, but that accounting shell game could be adjusted. When Utah's economic good times end, there's no telling where the state will get money to pay for vouchers, and they won't come cheap.

Fiscal analysts estimate that vouchers will cost about $9 million from the general fund the first year and $12 million the second. The cumulative cost is expected to be $429 million over 13 years, the time required to fully implement the program. By then, all Utah children will have had an opportunity to participate.

But it's all speculation.

In fact, there are many questions begging answers about the law's eventual drain on public education: How many and which children will leave? Will there be more money or less for public schools? Will there be a "brain drain," with mostly higher-achieving students from higher-income families heading to private schools? Will it help those minority and low-income students most at risk in underfunded public schools?

Voucher systems elsewhere can offer some insight, but Utah is plowing a lot of new ground after dark with this law. It's difficult to find an unbiased evaluation of other states' more limited systems, but one outcome is nearly universal: Academic achievement is not generally improved when students move from public to private schools with tax-supported vouchers.

There is another near-certainty: "Competition" from private schools - something touted by proponents of voucher systems - isn't apt to do anything to improve public schools unless and until both systems play by the same rules. Private schools pick and choose their students and set their own standards; public schools must educate all children and operate according to myriad state and federal rules.

The courts may have some say in Utah's evolving law. The Utah Constitution forbids public money going to religious schools. That could preclude vouchers at Catholic schools, which now enroll a third of Utah's private-school students, and new religion-based schools that may spring up to cash in on the new system.

If the five-year evaluation is negative, will the state abandon vouchers? We doubt it. For good or ill, Utah students are being cast as guinea pigs in a costly experiment to prove questionable hypotheses.