The Quebec government is violating the constitutional rights of immigrant parents by denying their children access to English-language public schools, the Supreme Court of Canada was told Monday.

And worse than that, said lawyer Brent Tyler, the policy could threaten the long-term viability of the English school system by eroding its student base.

Tyler reasoned that if all immigrants are directed to French public schools, the only source of new students for the English system will be interprovincial migration.

But statistics show there is actually a net out-migration of anglophones from Quebec, he noted. That leaves immigration as the only way for the English minority in the province to renew itself.

"If you accept the argument of the Quebec government, you are cutting to zero, for all practical purposes, any source or replenishment," Tyler told the high court.

Attempts to close loophole sparked challenge

It's the latest in a series of cases since the former Parti Quebecois government first brought in legislation in the 1970s limiting access to English schooling.

At issue this time is Bill 104, enacted in 2002 to close a loophole that allowed immigrants -- as well as some native-born francophones -- to skirt the rules and send their children to English schools anyway.

Over the years, parents began enrolling their kids in so-called "springboard" schools, private English institutions that received no funds from the provincial government and thus were exempt from the rules covering the public system.

After spending some time -- often as short as a single year -- in private classes the children could become eligible to transfer to English public schools.

The closure of that route by Bill 104 sparked a court challenge by 26 families whose children, about 100 in number, were denied access to English public schooling.

Estimates of the total number of transfers before the law was passed range up to about 8,000.

Quebec gov't: no "buying" constitutional rights

Tyler acknowledged that Quebec has the power to regulate access to its education system.

But a blanket ban on allowing any springboard students into English public schools goes too far and violates minority language guarantees in the federal Charter of Rights, he said.

Lawyers for the provincial government maintained the Charter must be read in the context of the unique social and historical circumstances of Quebec, where the majority francophone culture feels threatened by the English sea surrounding it in the rest of North America.

The Supreme Court ruled in the past that protection of the French language and culture are valid legislative goals for Quebec. It should uphold that principle in this case, said Benoit Belleau, one of the lawyers representing the province.

Colleague Francis Demers went further, saying newcomers to the province shouldn't be able to purchase access to English public schools by paying tuition for a year or two at a private school.

"It's really an issue of buying a constitutional right" said Demers.

Ottawa seeks middle ground

The federal government has tried to straddle the delicate issue, arguing that the Charter of Rights is national in scope but the exact "models" of minority language rights can vary by province.

"The situation of the francophone minority outside Quebec cannot be compared to the situation of the anglophones minority in Quebec," said federal lawyer Claude Joyal.

His written brief urged the court to avoid simplistic criteria and set guidelines for provincial administrators to take into account in assessing eligibility for English schooling.

The bottom line of the federal brief was that the claims of some of the 26 families should be rejected, but others should be upheld based on the particular legal issues raised.

The Supreme Court is expected to take several months to hand down a judgment.