A young protestor outside the federal courthouse in San Francisco

SAN FRANCISCO (CNN) -- A federal judge Wednesday refused to block a California ballot measure banning bilingual education from going into effect next month.

Proposition 227 requires all public-school classes in the state to be taught in English, rather than another language. Students who speak limited English would be taught in special one-year "English immersion" classes, then returned to regular courses.

After a three-hour hearing, U.S. District Judge Charles Legge said the measure -- approved by 61 percent of state voters in the June 2 primary election -- is constitutional, does not discriminate against any group and doesn't violate a federal law requiring schools to overcome students' language barriers.

He said requiring students to learn English through immersion in the language "is a valid educational theory," which is all federal law requires.

Unless an expected appeal to the 9th U.S. Circuit Court of Appeals is successful, Proposition 227 will go into effect the first week in August.

Uns

Opponents: Change will hurt minorities

Opponents claim that abolishing bilingual education, which has been used in California for three decades, unfairly targets minority students, particularly Hispanics.

They wanted Legge to issue an injunction that would have kept the measure from going into effect while they challenged it in the courts.

Some school administrators have also said they will be hard pressed to implement the ballot measure -- particularly putting in place the new immersion classes -- by the first week of August.

Escobedo

"It would cause immediate and profound disruption of the education of students who can least afford such disruption," argued Deborah Escobedo, a lawyer for the group Multicultural Education, Training and Advocacy, during Wednesday's hearing.

As Legge heard arguments inside, protesters gathered outside the federal courthouse in San Francisco with the message that "bilingual education works."

Ron Uns, who authored Proposition 227, hailed the judge's decision not to issue the requested injunction.

"For the first time now in California, almost all of those children will be taught English from the first day they enter school -- taught English as quickly and as effectively as possible," he said.

"I think the overwhelming majority of the parents will be happy that their children will finally be learning English in California public schools."