DES MOINES, Iowa (AP) — A judge dismissed a class-action lawsuit Tuesday that claimed Iowa’s state government systemically discriminated against black job applicants by allowing subtle racial bias to creep into virtually every hiring and promotion decision.

District Judge Robert Blink said the plaintiffs failed to prove their “unique legal theory,” which was based on research that suggests Americans inherently prefer whites to blacks, even if they are unaware they do.

The lawsuit, considered the largest of its kind against a state’s civil service system, covered up to 6,000 blacks passed over for jobs or promotions since 2003. It sought millions of dollars in lost wages and court-ordered changes to state hiring practices to better track and eliminate disparities.

Thomas Newkirk, the plaintiffs’ lead lawyer, promised an appeal.

“For those of you who are tired of the state spending its tax dollars on a broken system and knowing that the system will favor people who look like me over people who look like our clients, then you should be disappointed in this ruling,” Newkirk, who is white, said at a news conference. He added: “This is an historic case because it tried to approach discrimination from a different perspective.”

Unlike in typical discrimination suits, the plaintiffs did not argue that black applicants or workers faced overt racism or a discriminatory hiring test. Instead, they claimed managers throughout state government subconsciously favored whites through their decisions about who got interviewed, hired and promoted. They claimed state officials failed to follow their own hiring rules to prevent bias.

The case relied on the theory of implicit bias, which has received growing interest among employment lawyers after researchers developed the Implicit Association Test to test racial stereotypes. Their work has found an inherent preference for whites over blacks in about 70 percent of Americans, including among many who do not consider themselves racist.

University of Washington psychology professor Anthony Greenwald, who developed the test, testified on behalf of the plaintiffs that a similar percentage of Iowa managers likely had preferences for whites and that it could be a cause of hiring discrimination in Iowa.

Blink did not find the testimony persuasive. He said that Greenwald offered no data specific to Iowa and could not estimate what percentage of hiring decisions were the result of stereotyped thinking about blacks. The judge also said implicit bias “merely reflects attitudes” and did not mean discrimination occurred.

“Dr. Greenwald conceded that he would not use the phrase ‘implicit bias’ in writing a scientific article. How, then, should it import more gravamen in the court of law?” Blink wrote.

Greenwald called that nonsense Tuesday, saying the term is appropriate for public consumption but he would use more technical terms in studies. He said the ruling did not discredit the science behind the theory, but used other legal considerations to discard it.

“He’s saying because these studies were not done in the state of Iowa, we can ignore them,” Greenwald said.

Newkirk made a similar point. He said the science was clear that biases were present in Iowa, which is 91 percent white, and that would be one basis for appeal.

Iowa Attorney General Tom Miller, whose office defended the state, praised Blink for rejecting the theory. He noted that much of the case involved blacks who were passed over for jobs after sending in applications in which they did not list their race.

“This thoughtful decision is based on the law and on the facts,” he said.

Miller said the case challenged decisions related to nearly 500,000 applications submitted by 100,000 applicants for more than 20,000 jobs.

Blink said he was aware of the case’s heavy stakes and potentially historic nature, but he said the key questions were whether the legal claim could be allowed and if it was proven. He answered no to both.

He said the plaintiffs failed to challenge a particular practice that was discriminatory, an element required under state and federal law. And he said the data showed wide discrepancies in the hiring of blacks at different agencies, with some appearing to disadvantage blacks but others appearing to favor them. He also noted the number of black managers had increased over time compared to whites.

Blacks also fare better when applying for public employment in Iowa than the private sector, he said, which could prove that the state’s merit-based system was working.

Members of the lawsuit said they were disappointed but committed to the appeal.

“I just wanted to have a level field to play on and the state of Iowa didn’t do that and that’s why I became involved in this case,” said Butch Devine, who claims he was unfairly passed over for a job after a 27-year state career. “I don’t go along with the ruling, but we shall keep on fighting. This is just one day. Tomorrow’s another day.”

Copyright 2012 The Associated Press.