Six months after Californians voted to ban most bilingual programmes on the grounds that children were not learning English fast enough, the question of how to educate youngsters with limited English remains a contentious issue.

After a rancorous political battle, the English-only initiative, Proposition 277, was approved in June by 61 per cent of Californian voters.But the California Teachers Association, with 280,000 members, has joined a third suit aimed at blocking all or part of the law.

In a single, sweeping move, the proposition outlawed a variety of bilingual programmes in California state schools. It required that classroom instruction be “overwhelmingly” in English and contained an unusual provision that teachers could be personally sued by parents if they failed to comply. Damages would be used for private English tuition.

But the vagueness of the term “overwhelmingly” makes teachers liable to frivolous law suits, the CTA claimed. It joined civil rights groups in filing suit in a federal court, claiming that teachers’ constitutional rights were at risk, including their ability to speak freely to their pupils in the language of their choice.

CTA staff attorney, Priscilla Winslow, said: “We question what ‘overwhelmingly’ means. Does it mean 95 per cent of words uttered in the classroom must be in English? If it is a percentage, is it every day?” There are an estimated 1.4 million children in California schools who speak little or no English, the vast majority from immigrant families from Mexico and South and Central America. The law was “chilling and discouraging” for teachers assigned to them, Winslow said.

If a teacher identified a student as having particular trouble, she said,could they talk or give instruction in the child’s native language in a classroom during a lunch break or after hours?

The campaign for Proposition 227 pitted conservative school reformers against a coalition of teachers, educators and minority groups. Supporters said children would pass through “English immersion” classes more quickly, while opponents argued that slow learners with poor English were more likely to drop out entirely.

Since the introduction of the proposition, some school districts with heavy Latino minorities, such as San Francisco, are doing their best to work around it. They have exploited waivers that allow parents to declare an “educational need” for their children to remain in bilingual classes.

However, it is estimated that more than half of the children in California previously taught in their native language are now taught in English. Two earlier suits that claimed the new law denied equal opportunity in education, failed to win injunctions.

The speculation about law suits against individual teachers is not unfounded. Wealthy Silicon Valley entrepreneur Ron Unz, who heavily backed the initial campaign against bilingual education, has publicly offered to finance parents who wish to sue.

This month, his office sent a letter to 100 California school districts warning pointedly of the “personal legal liability” of educators who “wilfully and repeatedly” violate the initiative.