A new law aimed at ending ethnic-studies classes went into effect today.

For three years, state Superintendent of Public Instruction Tom Horne pushed the bill in hopes of terminating the ethnic-studies curriculum in the Tucson Unified School District.

House Bill 2281 bans classes in kindergarten through 12th grade that promote the overthrow of the U.S. government, promote resentment toward a race or class of people, are designed primarily for pupils of one ethnic group, or advocate ethnic solidarity.

If districts are found in violation of the new law, the Arizona Department of Education can withhold 10 percent of the district's state funding.

Horne has long criticized Tucson's ethnic-studies program, which he said divides students by race.

"A fundamental role of the public schools is to take students of different backgrounds and teach them to treat each other as individuals and not of the race they were born into. Tucson Unified District does it the opposite," Horne said. "They divide (students) by race and teach each group about its own background only."

Horne, who will be sworn in as state attorney general on Monday, will use his last hours as schools chief to enforce the law. The Republican leader said he will hold a "lame-duck session with himself" prior to the inauguration to announce the Tucson district violated the law.

At stake is nearly $15 million of state aid to the 53,500-student school district.

The violation declaration starts a 60-day process under the statute for Tucson to correct its program. Horne said his successor, John Huppenthal, will decide whether or not to withhold state funding.

Tucson school officials said that they support the law but that there is nothing in their curriculum that would run afoul of its provisions.

Incoming TUSD Superintendent John Pedicone said it's unclear how the district could be accused of breaking a law that hadn't yet taken effect without further scrutiny of the various courses.

"How do you declare a program in violation when you haven't observed a program in its current state?" Pedicone said.

The school board met in a special session Thursday to pass its third resolution on the issue, restating its belief that the ethnic-studies programs increase student achievement and directing district employees to ensure compliance with the new law.

The district integrates Mexican-American studies into its offerings, from kindergarten through high school. The courses are open to all students, and they draw a mixed crowd, though most of the students in the Mexican-American Studies classes - those that have drawn most of Horne's ire - are Hispanic.

It's unclear if the new law will affect any other school districts.

Mexican-American Studies Director Sean Arce and nine teachers within the department banned together and filed a federal lawsuit in October. The educators are opposed to the crackdown. The suit claims that the state law violates provisions of at least two constitutional amendments, including freedom of speech.

According to court documents, the teachers asked for an injunction, but the judge has not ruled yet.