Her order prohibits the district from "suspending, threatening to suspend, or otherwise punishing or disciplining the plaintiffs from wearing the bracelets."
The district's attorney, John E. Freund III, said he was disappointed by the ruling but had yet to confer with the school board about a possible appeal.
"It is inconceivable that the court did not recognize that the bracelets were meant to titillate," Freund said, noting that a porn actress had sought to associate herself with the bracelets and that truck stops were interested in selling them.
He added, "There's no group more distractible than 12- to 14-year-old middle school boys."
Carl W. Hittinger, the lawyer representing the two girls, could not be reached for comment.
Brianna Hawk, 13, and Kayla Martinez, 12, had been wearing the bracelets since the beginning of the school year when school officials decided to ban them, asserting that the slogan was a lewd double entendre.
On Oct. 28 - Breast Cancer Awareness Day - both girls were suspended a day and a half for wearing them to school.
Angela DiVietro, principal of Easton Area Middle School, testified at a December hearing that the bracelets could encourage sexual harassment.
The bracelets are distributed by the nonprofit Keep A Breast Foundation, which promotes breast-cancer awareness among young women under 30.
"We're extremely excited by the judge's decision," said Kimmy McAtee, marketing manager for the foundation, based in Carlsbad, Calif.
The foundation, which has a number of celebrity supporters, including singer Katy Perry, rejected the porn actress' request to market the bracelets, as well as inquiries by truck stops to sell them.
Contact staff writer Robert Moran at 215-854-5983 or firstname.lastname@example.org.