IOWA CITY, Iowa (AP) — After a 2007 report showed that Iowa had the nation's highest disparity for sending blacks to prison, state lawmakers took a novel step: They passed a law requiring analysts to draft "racial-impact statements" on any proposals to create new crimes or tougher penalties.

The governor at the time said the statements would be "an essential tool" to understand how minority communities might be affected before any votes are cast.

A review by The Associated Press shows that the first-in-the-nation law appears to be having a modest effect, helping to defeat some legislation that could have exacerbated disparities and providing a smoother path to passage for measures deemed neutral or beneficial to minorities.

Since Iowa acted, similar proposals have been adopted in Connecticut and Oregon. And more are likely to surface this year in several states.

Supporters say the idea can improve public trust at a time when many Americans question the fairness of the justice system and prevent policies that have unintended racial consequences. Critics are concerned that it unfairly injects race into policymaking and potentially weakens public safety. And a researcher who helps draft the statements said the analysis can involve some guesswork.

But there has been little analysis of how the laws actually work once passed. Iowa's experience provides the richest data available.

A review of 61 Iowa impact statements issued since 2009 showed that only 6 out of 26 bills seen as having a disproportionate effect on minorities passed both chambers and became law. Meanwhile, bills that were rated as having no effect or a positive effect on minority incarceration rates were nearly twice as likely to pass. Fourteen out of 35 such proposals became law.

The precise effect of the statements is impossible to gauge since many factors, including cost and lobbying pressure, contribute to whether a bill becomes law. But legislators say any warning that a law could send more minorities to prison or for longer sentences affects their debates.

"It's made a difference already here in Iowa," said former Rep. Wayne Ford, a Des Moines Democrat who wrote the law and is advising lawmakers across the country on similar legislation. "There is no doubt in my mind that what we started years ago has begun a movement, with Ferguson and all the public safety issues that we've got now."

An example arose last year when lawmakers considered a bill to extend the crime of interference with official acts to anyone who resists jail guards. At first, it seemed like an uncontroversial proposal to close a legal loophole. Police, correctional officers and municipalities lined up in support. But the plan died in a committee after analysts warned that 35 percent of those who commit the new crime would probably be minorities.

In a state that is 88 percent white, the heightened focus on race irritates some critics.

"What we have done is take the blindfold off of lady justice," said Republican Rep. Clel Baudler, a retired state trooper who leads the public safety committee. "A crime is a crime is a crime."

The statements are drafted by the Legislative Services Agency using data on the prison population, arrests, convictions and sentences broken down by race. The agency has found disproportionate racial effects in proposals to increase penalties for child kidnappers, pimps who bring minors into prostitution and suspects who elude police officers, among others.

Senior legislative analyst Beth Lenstra acknowledged that analysts are sometimes "kind of guessing" how a new crime would affect minorities using data from similar existing offenses. But she said the studies lead to a more informed debate.

Marc Mauer, director of the Sentencing Project, a nonprofit that pushes for criminal justice system changes, called the AP's findings "intriguing."

"We need to be a little cautious about interpreting that, but nonetheless, it's a fairly substantial difference right off the bat," said Mauer, whose 2007 report found Iowa blacks were 13 times more likely than whites to be incarcerated.

Mauer promoted racial-impact statements in a 2007 law journal article and worked with Ford to pass Iowa's law. His group hosted a two-day strategy session in August with supporters seeking to require racial-impact statements in several states, including Wisconsin and Arkansas.

Mauer said the measures "aren't going to change the world," noting that they do not affect laws already on the books, but they promote fairness.

The AP's findings are in line with a 2013 study by researchers at Simpson College, who concluded that Iowa's law has had a neutral effect on the prison population but may have a greater impact in coming years. With 2,130 blacks behind bars this month, they still make up 26 percent of the prison population and just 3 percent of Iowa residents.

Rep. Chip Baltimore, an Iowa Republican who heads the judiciary committee, said the statements were of little value since they do not consider the root causes of the racial disparity. But he said they offered political cover to lawmakers who oppose legislation for other reasons.

"I think at times it becomes a political tool," he said. "There are some legislators that if it has any minority impact, they won't vote for it."