The Ontario government will appeal a court ruling requiring it to pay for an expensive treatment program for autistic children, Attorney General Michael Bryant said Monday.

Justice Frances Kiteley of the Ontario Superior Court sided with 30 families with autistic children who argued that the government was wrong to stop the treatment when the children reached the age of six.

The ruling means Ontario may have to start paying between $30,000 and $80,000 a year to provide applied behavioural analysis (ABA) for older children.

But Bryant said Monday that the Supreme Court of Canada has previously ruled in support of a province's right to decide which programs are appropriate.

Earlier, Premier Dalton McGuinty said he doesn't like the idea that a court can tell the government to spend money without identifying a source for the money.

"We're always concerned when you get a court-mandated expenditure," he said.

Treatment funding under fire

Since 2000, the province has been paying for the treatment for younger children, but cut off the money when the children turned six.

Thirty families filed a lawsuit as a result, arguing that their children were being discriminated against on the basis of age.

In her decision, Kiteley wrote that "the defendant has violated the rights of the infant plaintiffs."

The 209-page ruling grants relief and damages for past and future therapy for the families involved.

If the province's appeal fails at the Ontario Court of Appeal or at the next level, the Supreme Court of Canada, the government may not be able to deny ABA funding to any autistic child in Ontario.

A Supreme Court of Canada ruling on the matter might also require governments of other provinces to fund ABA treatment for all age groups, if they currently pay for younger children.

In a related decision last fall, the Supreme Court of Canada refused to order the B.C. government to fund the intensive treatment, saying the province had the right to set its own priorities for health-care funding.

Medical experts believe that autism spectrum disorder affects as many as one in 250 Canadian children, causing mild to severe impairment of social, behavioural and communication skills.

Applied behavioural analysis works by leading patients through multiple repetitions of a wide variety of actions appropriate for children of their age.