In a 13-page ruling, U.S. District Judge Robert S. Lasnik said three Seattle-area residents could be required to observe the ritual while participating in competitions.
James and Leilani Akiyama, 17 and 14, and Jay Drangeid, 40, all of Bellevue, had fought the rule, saying it amounted to a religious ritual being imposed on them. A 1997 injunction has allowed the three to compete in U.S. judo matches without performing the ritual.
"Virtually any restriction or regulation imposed by a public accommodation could impinge upon a person's religious beliefs," Lasnik wrote in dismissing the injunction Thursday.
Jim Bregman, president of the Colorado-based U.S. Judo Association, one of several organizing groups for the sport, praised the ruling.
"It's clear the bow in judo is simply a respectful act, like a handshake in wrestling," Bregman said.
John Holm, the Akiyamas' stepfather and operator of a judo training center, said they might appeal the decision.
"We have a half-dozen Muslim kids who want to compete in the state championships coming up January 26 and they can't compete because of their religious beliefs," Holm said.
Competitors in judo, which has its roots in Shintoism, bow several times during competitions, usually to a portrait of Jigoro Kano, the Japanese founder of the sport. Bowing is mandatory in international competitions.