A court ruling on Tuesday striking down job protections for teachers in California deals a sharp blow to unions — and will likely fuel political movements across the nation to eliminate teacher tenure.

Los Angeles Superior Court Judge Rolf M. Treu found five California laws governing the hiring and firing of teachers unconstitutional. But it was his language, more than the ruling itself, that will shake the political debate.

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Treu found that the statutes permit too many grossly incompetent teachers to remain in classrooms across the state — and found that those teachers shortchange their students by putting them months or years behind their peers in math and reading.

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He ruled that such a system violates the state constitution’s guarantee that all children receive “basic equality of educational opportunity.” In a blunt, unsparing 16-page opinion, Treu compared his ruling to the seminal federal desegregation case Brown v. Board of Education, decided 60 years ago last month. “The evidence is compelling. Indeed, it shocks the conscience,” Treu wrote.

In adopting the language and legal framework of the civil rights movement, Treu gave a major boost to school reformers from both parties who have long argued that the current system dooms poor and minority students to inferior educations.

He might also have put further strain on the already-shaky alliance between teachers unions and Democrats.

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In recent years, high-profile Democrats — up to and including President Barack Obama — have broken with their traditional union allies over issues such as charter schools, standardized testing and the feasibility of evaluating teachers by how well their students perform on standardized tests. But many other Democrats in state legislatures and Congress remain loyal to teachers unions. Those ties are especially strong in California, where the unions wield strong political influence. The ruling’s scorching finding that union policies violate students’ civil rights could put those longstanding loyalties to the test.

Indeed, even before the verdict, members of the plaintiffs’ team were talking confidently about plans to present their evidence to California Gov. Jerry Brown, a close ally of the teachers unions, to prod him into joining the reformers’ side, at least on key issues such as teacher tenure.

Reformers also plan to take the fight to other states, hoping the strong language of the ruling will prompt Democrats elsewhere to reconsider ties to teachers unions. They’re considering similar lawsuits in Connecticut, New Jersey, New Mexico, New York, Oregon and elsewhere. And they plan a relentless public relations campaign, backed by millions of dollars from reform-minded philanthropists, to bring moms, dads and voters of both parties to their side.

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Jim Finberg, a lawyer for both major California teachers unions, said he wasn’t worried by the ruling or the coming public relations juggernaut. The case, he said, was all about “busting the teachers union,” not supporting children. “People who really care about education will see through that,” he said. “The truth will out.”

Randi Weingarten, president of the American Federation of Teachers, echoed those comments, accusing the plaintiffs of seeking to divide and conquer rather than support public schools. “The other side wanted a headline that reads ‘Students win, teachers lose,’ ” Weingarten said. “This is a sad day for public education.”

But Education Secretary Arne Duncan signaled his support for the ongoing campaign to reform hiring and firing laws. He noted that “millions of young people in America … are disadvantaged by laws, practices and systems that fail to identify and support our best teachers and match them with our neediest students.” And he called the ruling “a mandate to fix these problems.”

The Education Department has been slowly drafting a plan to nudge states to better distribute effective teachers.

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Though the ruling was couched as “preliminary,” there was nothing tentative about Treu’s opinion. He found “no dispute that there are a significant number of grossly ineffective teachers currently active in California classrooms” and that the legal system protects them by making it all but impossible for districts to fire even the worst teachers.

He also expressed outrage at a system that shields veteran teachers from layoffs, regardless of their competence. “The logic of this position is unfathomable and therefore constitutionally unsupportable,” he wrote.

What’s more, Treu added, evidence at trial showed that teacher protections embedded in California law disproportionately hurt black and Hispanic students, who are far more likely than their peers to be assigned truly bad teachers.

The California Federation of Teachers and the California Teachers Association plan to appeal to the state Supreme Court. Treu decided the disputed laws should remain in place pending that appeal. He will also take both sides’ comment under advisement before finalizing his ruling within the month.

Teachers unions, who have the money and the membership to exercise considerable clout in many state legislatures, defend tenure, seniority and other job protections as simply guaranteeing due process. They accuse reformers of spending big to demonize teachers and weaken unions instead of tackling other forces that affect academic achievement, such as poverty, crime and inadequate state funding.

“Let’s be clear,” said Dennis Van Roekel, president of the National Education Association. “This lawsuit was never about helping students, but is yet another attempt by millionaires and corporate special interests to undermine the teaching profession and push their own ideological agenda on public schools and students while working to privatize public education.”

Van Roekel added that the ruling will “make it harder to attract and retain quality teachers and ignores all research that shows experience is a key factor in effective teaching.”

The closely-watched case, Vergara v. State of California, was brought by nine students who said their education suffered because they were stuck in classrooms with lousy teachers who failed to challenge them, inspire them or even maintain basic discipline. Plaintiff Julia Macias, who will be entering high school in the fall, hailed their victory as proof that “students have a voice and can demand change when we stand together.”