American Federation of Teachers President Randi Weingarten expects to see more challenges to “value-added” teacher evaluations. (Damian Dovarganes/Associated Press)

Opponents of the nation’s teacher unions won a landmark victory last year in a California lawsuit that challenged tenure protections, a case that became the beginning of a national effort to roll back teacher tenure laws in state courts.

Now the largest unions in the country are using a similar tactic, as teachers turn to the courts to fight for one of their most pressing interests: An end to test-based evaluations they say are arbitrary and unfair.

The lawsuits show that two of the nation’s most contentious battles over the teaching profession are shifting from legislative arenas to the courts, giving judges the chance to make decisions that could shape the way teachers are hired, fired and paid. Union critics and wealthy advocates have hired lawyers to take on the teachers; the teachers, through their unions, have gone before the bench to go after state officials and their policies.

The latest foray into the courtroom began Feb. 13, when New Mexico teachers sued state officials over an evaluation system that relies heavily on student test scores. Tennessee teachers also sued their state officials this month, arguing that most teachers’ evaluations are based on the test scores of students they don’t actually teach. Florida teachers brought a similar lawsuit last year; it is now in federal appeals court, while other complaints are pending in Texas and New York.

Union officials say they expect to see more lawsuits in the future, especially over evaluations that use complex and controversial algorithms — called “value-added models” — to figure out how much of a student’s learning can be attributed to their teacher.

“There will be more challenges because things are not being seen as credible and fair,” said Randi Weingarten, president of the American Federation of Teachers, which joined the New Mexico lawsuit. “What we’ve gotten to is this routinized, mechanized displacement of human judgment, and that’s what I think you’re seeing — that is the underlying issue that is the root of this agita about evaluations.”

“It’s ridiculous that we have to go to the courts,” Weingarten said. But she said that New Mexico education officials and other supporters of test-based evaluation are deaf to evidence that the evaluations aren’t working.

Critics say that the unions are exaggerating both the problems associated with value-added scores and the weight that they carry in evaluations. Value-added scores account for up to 50 percent of evaluations in some states, and a smaller portion in many others, with the remainder of teachers’ ratings comprised of classroom observations and other measures.

“Essentially teacher unions don’t want any evaluation,” said Eric Hanushek, an economist at Stanford University’s conservative Hoover Institute and a supporter of value-added measures. “That’s what they’re angling for.”

Until recently, teachers’ evaluations in many jurisdictions were based almost exclusively on principals’ observations, and the vast majority of teachers were rated satisfactory. But the Obama administration made test-based evaluations a requirement for any state that wanted to compete for Race to the Top grant money or win relief from the federal No Child Left Behind law.

Now 35 states require student achievement to be a significant factor in teacher evaluations, and many school districts are using those evaluations to make decisions about teacher bonuses and as a basis for firings.

Most states are using the value-added models to determine how much teachers contribute to their students’ achievement on standardized tests. But only a fraction of teachers teach subjects and grade levels that are tested.

Art and music teachers, for example, have no such tests. In some states, those teachers are assigned a score anyway, either based on how their students performed on tests in other subjects or based on the performance of all students in a school.

A plaintiff in the Florida case is a calculus and algebra II teacher whose students are mostly high school juniors and seniors. But her value-added score — which accounted for 50 percent of her evaluation — was based on the reading scores of 9th- and 10th-graders.

A federal district court judge opined last year that Florida’s evaluations were unfair, but also found that they are legal. The Florida teachers have appealed and the case is now before the 11th Circuit Court of Appeals. Tennessee teachers filed a similar lawsuit in early February.

“We believe in teacher evaluation, when done right,” said Lily Eskelsen García, president of the National Education Association, the nation’s largest teachers union, which has helped argue the cases in Florida and Tennessee. “No one who cares about our students and schools can explain why it is sensible to evaluate teachers, and make high-stakes employment decisions about them, based on a measure of student learning that is completely unrelated to what those teachers are trained, licensed and employed to teach.”

In other cases, including in Rochester, Syracuse, Houston and in Knox County, Tenn., teachers have taken a different legal approach, attacking the value-added models as arbitrary and unreliable.

A growing number of groups have voiced skepticism about the validity of value-added models. The National Research Council, the American Statistical Association and the Rand Corporation have all cautioned against using value-added scores to make personnel decisions.

Others believe that value-added scores offer valuable information and are no more flawed than other evaluation methods, such as classroom observations that can be skewed by a principal’s bias.

“My sense is that all of the measures are flawed, but they all also are useful. They’re all better than nothing but none of them is perfect,” said Morgan S. Polikoff, an assistant professor of education at the University of Southern California who has researched evaluation methods.

The latest union complaint, in New Mexico, argues that the evaluations violate teachers’ due process rights because they are “based on flawed methodology, erroneous records, and inaccurate data.”

“This system doesn’t make sense,” said John Simms, an Albuquerque middle-school social studies teacher who was rated effective, but who said his value-added score tells him nothing useful about how to improve. “If we can’t make heads or tails of it as educators, how’s it supposed to help us help kids?”

The New Mexico lawsuit says that there were widespread errors in the new evaluations because of a rushed rollout and faulty data, including incomplete or wrong test scores. And it says that some teachers were docked for absences that should have been protected under the federal Family and Medical Leave Act. Attendance counts for up to 10 percent of evaluations in New Mexico, and teachers lose points for taking sick or personal days, even if such leave is allowed under their contracts.

[A closer look at four New Mexico teachers’ evaluations .]

Albuquerque teacher Pamela Crone said she missed four months of school last year after she fell on a wet floor in the school building and suffered a brain injury. She received zero out of 40 possible points for attendance, which pushed her into the “minimally effective” category.

“It was just so incredibly unfair,” said Crone, who resigned at the end of last year because of ongoing health problems. “I’ve got 36 years of really excellent evaluations and to have had that put down in writing about me, it just was not right.”

Ellen Hur, a spokeswoman for Skandera, said that New Mexico state officials have not been served with notice of the most recent complaint. “However, if there is yet another lawsuit from the AFT, this is getting ridiculous,” Hur said.

“It’s time for the union to stop obstructing and wasting taxpayer dollars so we can focus on serving our students and improving our education system, instead of wasting precious time and resources on yet another baseless lawsuit,” she said.