Republican lawmakers in Wisconsin were operating in a "fact-free cocoon" of partisan prejudice when they claimed that voter fraud was a major problem in their state, wrote federal judge Richard Posner in 2014. "If the Wisconsin legislature says witches are a problem, shall Wisconsin courts be permitted to conduct witch trials?"

Posner is a conservative appointed by Ronald Reagan. But in the best tradition of the law, he places evidence ahead of ideology. For example, in 2007, he authored a key opinion upholding an Indiana voter ID law. Seven years later, when the Wisconsin case arose, he changed his mind based on new information.

"There is compelling evidence that voter impersonation fraud is essentially nonexistent in Wisconsin," he wrote. The legislature was using chicanery "as a mere fig leaf for efforts to disenfranchise voters."

We thought of Posner's opinion this week when the Supreme Court voted to overturn two laws from Texas aimed at blocking access to abortion services. The Texas legislature maintained that the laws were necessary to protect women's health, but the High Court -- like Posner in the Wisconsin case -- reviewed the evidence and rejected the state's argument.

One law required abortion providers to have admitting privileges at local hospitals; the other mandated unreasonably high medical standards for abortion clinics. As a result, half the state's 40 clinics have closed. Justice Stephen Breyer, writing for the court, said the Texas laws clearly imposed an "undue burden" on women seeking abortions, a test laid down by the justices in 1992. In fact, Breyer added, the state presented no evidence that the laws "would have helped even one woman obtain better treatment." Just because a legislature, or a politician, declares something to be true does not make it so.

Breyer is a well-known liberal who once worked for Ted Kennedy and was appointed by Bill Clinton. He was joined in his opinion, however, by Justice Anthony Kennedy, who -- like Posner -- was a Reagan appointee.

During more than 28 years on the bench, Kennedy has generally sided with anti-abortion forces, but he's also been willing to part with conservative orthodoxy when the facts warrant flexibility.

In an essay on Kennedy in The Washington Post, legal scholar David Cole wrote: "Breaking with one's peers and rethinking one's commitments are not easy. In our increasingly divided political culture, many of us rarely do. But it is a welcome sign of an open mind, an attribute especially important in those who hold the power to enforce constitutional law."

Let's be clear: We are not discussing the morality or even the advisability of abortion (in fact, the two of us disagree on those issues). We are talking about the critical importance of basing public policy on facts, not fantasy; on evidence, not prejudice or prevarication.

As Cole notes, this is especially important at a time when "our increasingly divided political culture" makes rational exchanges so much more difficult. A recent survey by the Pew Research Center shows how the growth of hyper-partisanship clouds the ability of loyalists on both sides to agree on a common set of facts and trust each other's good will.

Half of all Republicans view Democrats as more "closed-minded than other Americans," while 7 in 10 Democrats disparage Republicans that way. Almost half of all Americans find it "distressful and frustrating" to talk politics with people who hold different opinions; 6 of 10 say that when they do have those discussions, they feel they have "less in common" with the other side than they originally thought.

And partisan hostility is rising rapidly. Today, 58 percent of all Republicans hold "very unfavorable views" of Democrats, up from 32 percent in 2008. Fifty-five percent of Democrats are equally disdainful of Republicans, compared to 37 percent eight years ago.

Closed-mindedness is an epidemic, like Ebola or Zika. Much of the country is infected with the feverish mindset Posner warned about, declaring that "witches are a problem" and then launching crusades to eradicate those nonexistent threats.

Donald Trump is the worst offender, defying reality daily with fear-mongering accusations about "rapists" from Mexico and terrorists from Syria. But he's not alone. Bernie Sanders sees plenty of "witches" on Wall Street and in corporate boardrooms.

Just about every presidential candidate in both parties has endorsed "litmus tests" and promised to pick judges with closed minds and preconceived opinions on a range of hot-button issues.

American politics and jurisprudence need more unfettered thinking and less unreasoning rigidity. Those self-made, air-tight "fact-free cocoons" can be pretty suffocating.

– By Steve and Cokie Roberts, NEA Columnists