LOS ANGELES (AP) — The effort to have parents drive school reform received a substantial boost with a court ordering a San Bernardino County school district to accept a parent petition demanding changes at a failing elementary school.

The case is seen as an important test of California's so-called "parent trigger" law, which allows parents to force reforms at low performing schools through a petition signed by 50 percent of parents. The 2010 law was the first of its kind in the country and has inspired similar versions in several other states.

It also has also sparked fierce resistance from teachers unions and school districts, which have fought the first two cases in California. In the first case, Compton Unified School District successfully defeated a parent petition on a technicality last year in court.

In the closely watched second case, involving the Adelanto Elementary School District, the issue has centered on parent signature rescissions.

Superior Court Judge Steve Malone ruled late Friday that rescissions are improper, a key victory for parent reformers who have seen their petition drives undone by opponents mounting campaigns to convince signers to rescind their signatures.

Malone said signatures cannot be rescinded and stated that the district's acceptance of rescissions, which caused the number of validated signatures to fall below the 50 percent threshold, was "an abuse of discretion."

He ordered the district to accept the petition filed by the Desert Trails Parents Union within 30 days and to immediately seek proposals from charter school operators to take over Desert Trails Elementary School in Adelanto, located about 90 miles northeast of Los Angeles.

Ben Austin, executive director of the Los Angeles-based nonprofit, Parent Revolution, which helps organize parents and guide their campaigns, said it was the first ruling in the nation to uphold a parent-trigger law.

"They are the first parents to take control of the educational destiny of their children," he said at a press conference. "This is a new paradigm of parent power."

School board President Carlos Mendoza said the board has not yet discussed the ruling, but he will recommend that the board file an appeal based on the parents union strategy of having parents sign two petitions: one calling for wide-ranging reforms and another calling for charter school conversion if reforms were not implemented.

He said parents were more in favor of the first petition, but the second one was submitted instead.

Mendoza said the move was misleading.

"I call it bait and switch," he said. "I am not concerned about converting Desert Trails into a charter school as long as the board has a say with community input on what that charter school will be. I do not believe the two petition strategy should be acceptable nor allowed to be used again anywhere."

Desert Trails parent organizers also said they found evidence that several petition signatures had been fraudulently altered to show rescissions. The district invalidated those rescissions.

"This is a huge milestone in our struggle for our children to receive the basic education they are entitled to and deserve," said Doreen Diaz, lead petitioner and coordinator of the Desert Trails Parent Union.

Parents' complaints about Desert Trails, where just 35 percent of children last year tested proficient in English and 46 percent in math, ranged from curriculum to homework to discipline. The school has been classified as failing for the past six years.

The district plans to implement a reform plan in September, including lengthening the school day by 30 minutes. But parents said it was too little, too late.

Parent Cynthia Ramirez was emotional as she spoke at the press conference, saying that the ruling gave her hope that her children would now get the educational foundation they needed in order to progress to college.

"It's our kids," she said. "We can't back down."