Want to hurt kids? Put state bureaucrats in charge of evaluating the schools in school choice programs. Recent events in Louisiana show how this undermines schools and hurts kids. But the education blob in Oklahoma apparently cares more about enforcing the government monopoly than about what delivers a good education to kids who need it.

School choice is on the march in Oklahoma. The state Supreme Court recently gave one of its two choice programs a unanimous thumbs-up. The next day, a bill to create education savings accounts passed out of committee in the state legislature.

No good deed goes unpunished! A bill was introduced to saddle all private schools in all of the state’s school choice programs (current and future) with a new albatross: the Oklahoma School Testing Program. The program includes state-issued A-F school report cards, which would now be given to private schools if the bill passes.

These kinds of requirements are usually defended in the name of “transparency.” People think it can do no harm because schools aren’t officially sanctioned based on the test scores. They only have their scores and corresponding grades published—it’s just information, so what’s the harm?

Tell that to the Louisiana kids whose education was ruined by exactly this kind of “transparency.” Louisiana’s voucher program requires participating private schools to take the state test. Recent research on the effect of this requirement is now rocking the education world; Oklahoma would do well to take note.

Louisiana’s is now the first school choice program ever shown by empirical research to produce worse academic outcomes. The existence of the program actually hurts kids. And we’re not talking about a small difference; the negative finding is very large. Students’ chance of getting a failing grade went up by 50 percent.

A choice program that actually hurts kids is an amazing feat. It’s literally one of a kind. Everywhere else in the country, school choice has been a consistent winner for kids. Outside Louisiana, choice has been studied 16 times with random-assignment methods, the gold-standard scientific method used in medical trials. Of those studies, 14 found participating students had better academic outcomes, and the other two found no difference.

That makes perfect sense. Giving families an additional choice helps them. They don’t have to switch schools, but they can if it’s beneficial.

That of course is on top of the other benefits of school choice. Out of 30 empirical studies, 28 find choice improves academic outcomes at public schools, because the schools can no longer take students for granted. Out of 28 empirical studies, 25 find that school choice saves money for taxpayers. There’s also a strong empirical research consensus that choice improves racial segregation and strengthens civic values and practices like toleration for the rights of others.

So what on earth happened in Louisiana? “Transparency” happened, that’s what.

Tests are not neutral. If you control the test, you control the curriculum. What gets taught is determined by what gets tested.

Allowing the state to test the schools gave politicians power over the schools, and the schools refused to accept it. Private schools don’t like limitations on what students they can take or what they charge, and rightly so. Such limitations damage education. But schools will typically put up with that to participate in a choice program, because they want to serve kids.

However, most schools absolutely will not allow outsiders to tell them what to teach. That’s surrendering the essence of the school. Admittedly, there are exceptions—in Indiana, for example, almost all private schools give the state test, and did so long before the state had any school choice programs. In that state, there is a longstanding tradition of trust that the state won’t abuse that power. Absent such unusual conditions, however, private schools rightly reject the extension of state power into the content of the classroom.

The research shows that’s exactly what happened in Louisiana. Amazingly, fewer than one-third of Louisiana private schools chose to participate in the program in its first year. That’s a sharp contrast to every other school choice program, where private schools are eager to participate in order to serve more kids. Survey research finds that fear of “future regulations” was the number one reason cited by private schools choosing not to participate.

The focus on “future regulation” shows what the real problem here is. Once the state has this power over schools, there are no guarantees about how it will be used—even if present circumstances make abuses unlikely in the short term. As Ronald Reagan said: “A bird on a tether, no matter how long the leash, can always be pulled back into the cage.”

The enforcers of the government school monopoly made clear their intention to use this power. John White, Louisiana’s state superintendent of education, issued the vague and arbitrary threat that schools could be suspended if results on state tests “don’t meet expectations.” He also reminded them that schools “are not permitted to accept new scholarship students until their results align with program requirements.”

Schools choosing to join and remain within a choice program in spite of such threats are likely to be the worst-performing schools. Tellingly, one group of researchers note that “survey data show that [voucher] eligible private schools experience rapid enrollment declines prior to entering the program, indicating that the [voucher program] may attract private schools struggling to maintain enrollment.” Where schools have to trade away their very essence in order to participate, only schools that are desperate for cash flow (i.e., the worst schools) can be expected to enter the program.

The proposed Oklahoma law would also submit private schools to the state’s school grading system. (Louisiana did this too, but only for schools with at least 10 voucher students.) Adding a school grade on top of the test scores creates an additional opportunity for political manipulation of the system.

History shows politicians are not slow to seize this opportunity. In the past, several states have been caught red-handed rewriting the formulas determining what scores earn what grades for political, not educational, reasons. Forcing choice schools to submit to the grading system gives politicians the power to invent a formula for cooking up school grades that will make the private schools look worse.

You’re a fool if you think the government school monopoly wouldn’t try to use that power to hurt private schools—if not now, later. And private school leaders are no fools. Louisiana shows that. And if Louisiana’s private school leaders saw it coming, how much more will Oklahoma’s, given that they have Louisiana before them as an example to learn from?

If private schools in Oklahoma’s school choice programs are required to submit to a state test with state grades, prepare for an exodus of all the good private schools out of the programs. And then you can explain to the kids why they’re not allowed to get a good education any more.

Let families grade schools. Politicians have proven they’re not up to the job.

Greg Forster (Ph.D., Yale University) is a senior fellow with the Friedman Foundation for Educational Choice. He is the author of six books, including John Locke’s Politics of Moral Consensus (Cambridge University Press, 2005) and Joy for the World: How Christianity Lost Its Cultural Influence and Can Begin Rebuilding It (Crossway Books, 2014). He has written numerous articles in peer-reviewed academic journals, as well as in popular publications such as the Washington Post and the Chronicle of Higher Education.