A court ruling that California parents "do not have a constitutional right" to home-school their children has touched off anger and bewilderment throughout America's home-schooling community and prompted a denunciation from Gov. Arnold Schwarzenegger.

For a movement that has gained greater accommodation in recent years, a state appellate court decision last month is a setback that, if not overturned on appeal, could force some 166,000 home-schooled students in California to enroll in conventional schools. It may also prod California and other states with vague or nonexistent laws on home schooling to be more specific about what is allowed and what is required of home-schoolers.

California's education statutes, for instance, do not mention "home schooling," but officials have allowed the practice for decades. The appellate court, however, found that the state's laws have not been changed to allow home schooling since a case back in 1953 erected a major roadblock to the practice.

Governor Schwarzenegger said Friday he would go to the legislature if the ruling is not overturned.

"I could see this ruling being a real strong impetus for home-schoolers in California to get the legislature to change their laws.... Or I could see it being perhaps the beginning of other states wanting to look more closely both at their laws and current enforcement," says Kimberly Yuracko, a professor at Northwestern University's Law School in Chicago.

The number of students nationwide who are home-schooled is not known because 10 states are so hands-off they require no reporting at all, nor do parents always comply with reporting requirements. Estimates range from 1.1 million to 2.5 million home-schooled students, and the numbers are rising.

About half the states require more than simple notification from parents or guardians, such as testing, curriculum approval, or home visits. But such rules are dwindling – either explicitly or by lax enforcement, say experts. Home-school advocates worry the California case could bring more regulation or enforcement, or both.