A Los Angeles judge Tuesday struck down teacher tenure and other California laws that offer job security to educators, a decision that is expected to trigger widespread challenges of teacher job protections nationwide.

Plaintiffs in the case argued that California children who are poor receive an inferior education because they are saddled with the weakest teachers, who are entrenched in their jobs and are difficult to fire. Superior Court Judge Rolf Treu sided with the plaintiffs against some of the most powerful labor unions in the country, striking down California’s teacher employment laws because he determined that they violate students’ civil rights.

Calling it a landmark decision, attorneys for the plaintiffs said that California was just the start of a planned effort to knock down tenure in a state-by-state campaign across the country. Those who have opposed tenure — from the right and the left — have long said that the protection is an impediment to stronger U.S. education because it keeps bad teachers in the nation’s classrooms. Tuesday’s decision could mark a new front in national education reform, with attacks on tenure moving into the courtroom.

“This is going to be the beginning of a series of these lawsuits that could fix many of the problems in education systems nationwide,” said plaintiffs attorney Theodore Boutrous, who was joined in the effort against tenure by former U.S. solicitor general Ted Olson. The same legal team won a U.S. Supreme Court victory that allowed same-sex marriages to resume in California. “We’re going to roll them out to other jurisdictions.”

Boutrous and Olson were among several prominent lawyers hired by Silicon Valley mogul David F. Welch, founder of an optical telecommunications firm, who created Students Matter, an advocacy group, to challenge teachers unions in California. Welch pumped several million dollars into the effort. Students Matter is considering similar lawsuits in New York, Connecticut and other states with teacher job protections similar to those in California, Boutrous said.

Read the ruling A California judge ruled that the state's teacher tenure rules violate the civil rights of students, as the worst teachers end up in the highest-poverty schools, creating unequal conditions. Read it.

The ruling was a serious blow to labor unions, whose core mission is to protect teachers’ jobs. The judge issued a stay pending an appeal by the unions, and a final resolution could take years.

John Deasy, superintendent of the Los Angeles Unified School District and a witness for the plaintiffs, called it a “historic day.”

“We can rectify a catastrophe,” Deasy said. “We can and will and must assure that children have the most effective teachers in their classrooms every day. Not some children, not most children, not even nearly all children. But all children.”

Labor leaders said the case is part of a broad assault on unions, since government workers make up more than half of the nation’s union membership.

“Let’s be clear: 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,” Dennis Van Roekel, president of the National Education Association, said in a statement.

Randi Weingarten, president of the American Federation of Teachers, said the lawsuit focused on the relatively small pool of “grossly ineffective” teachers — estimated at 1 to 3 percent of California’s 275,000 teachers — and ignores other factors that affect the quality of education, especially for poor children.

“It’s surprising that the court, which used its bully pulpit when it came to criticizing teacher protections, did not spend one second discussing funding inequities, school segregation, high poverty or any other out-of-school or in-school factors that are proven to affect student achievement and our children,” Weingarten said.

Tenure and related employment laws in California protect teachers from arbitrary firings, reward experienced teachers and make teaching an appealing career option, Van Roekel said. The ruling will make it more difficult to attract and retain high-quality teachers, he said.

But the plaintiffs argued that California’s laws make it too difficult to get rid of ineffective teachers, costing $450,000 and taking 10 years in one case, according to one trial witness.

In a 16-page ruling, in the case of Vergara v. California, Treu struck down three state laws as unconstitutional. The laws grant tenure to teachers after two years, require layoffs by seniority, and call for a complex and lengthy process before a teacher can be fired.

Treu said the evidence presented at trial “is compelling. Indeed, it shocks the conscience.”

Defendants in the case, including Gov. Jerry Brown (D) and other state officials, were joined by the California Teachers Association and the California Federation of Teachers.

In many ways, the case was a proxy fight for some of the national conflicts over the teaching profession.

Backing Welch were some of the most incendiary players in the fight over the future of public schools, including Michelle A. Rhee, the former schools chancellor in Washington who got rid of tenure in the District in 2009 and went on to form an advocacy group aimed at eliminating it across the country.

“It is my hope that this movement continues on the national stage for all of our students,” said Rhee, who is now chief executive of Students First.

For the unions, the ruling poses a serious threat to tenure, which was first adopted by New Jersey in 1909 to protect teachers from firings on the basis of race, pregnancy, politics or other arbitrary factors.

The California unions have staved off attempts to change the laws through the legislature, leading Welch to try through the courts.

Welch used a novel civil rights approach, arguing that poor and minority students in California are being denied their right under the state constitution to equal access to public education because they are more likely than affluent white students to be taught by “grossly ineffective” teachers.

Under the laws struck down by the court, school districts have about 18 months after a teacher is hired to award tenure. That is not enough time to make a valid decision, the judge found, noting that California is one of only five states with a period of two years or less. Thirty two states have a three-year period and nine states have four- or five-year periods. Four states have no tenure system.

The complaint also attacked seniority rules and “last in, first out” policies, which say the newest teachers are the first to be laid off when jobs are cut, regardless of performance.

Since 2010, Republican governors and legislatures have been trying to eliminate or weaken teacher tenure laws. Jeb Bush, former governor of Florida and a potential Republican presidential candidate who heads an education foundation, applauded the ruling, saying, “Its impact will be felt well beyond California.”

Some Democrats also joined in cheering Tuesday’s verdict.

Rep. George Miller (Calif.), an old-school liberal and the top Democrat on the House Committee on Education and the Workforce, suggested that the anti­tenure movement ought to spread beyond California. “It is not only Californians who should celebrate today’s decision, but families in every state and school district across the country,” Miller said. “Unfortunately, school districts nationwide have policies in place that mirror those challenged in Vergara. . . . This is simply indefensible. Today’s ruling puts every school with similar policies on notice.”

U.S. Education Secretary Arne Duncan also criticized tenure laws.

“The students who brought this lawsuit are, unfortunately, just nine out of millions of young people in America who are disadvantaged by laws, practices and systems that fail to identify and support our best teachers and match them with our neediest students,” Duncan said in a statement.