A HIGH Court victory by Brazilian student Marcos Berenguel is increasing the already considerable pressure on Australia's skilled migration policy.

It allows graduates to overturn the refusal of skilled migration visas on the basis that the Department of Immigration and Citizenship failed to take into account up-to-date English test results.

"It wouldn't be an exaggeration to say there could be thousands [of former foreign students] to take advantage of it," Sydney immigration lawyer Peter Bollard said.

Immigration Minister Chris Bowen has launched court challenges to try to limit the fallout from the Berenguel case.

If Berenguel helps some former students, others with applications in an already long queue will be pushed back as the government sharply reduces the number of places for independent skilled migrants. This category was blown out by student demand, distorting the migration program, the government said.

In March, the High Court found for Mr Berenguel, saying it was absurd and unfair for the department to refuse to accept an English test result that came in after his application for permanent residency as a skilled migrant.

Under the rules, Mr Berenguel had to show results from "a test conducted not more than two years before" the visa application.

But there was plenty of demand for an International English Language Testing System test, which enjoys an immigration monopoly, and Mr Berenguel could not book an exam until a month after his visa application.

The High Court said the rules simply meant he had to show "recent competency" in English.

The case has created a boom in retesting because there are long delays between visa application, a decision by the department, and any review by the Migration Review Tribunal. Former students, required by the rules to get higher IELTS scores these days, can take tests right up to a tribunal hearing.

"I've seen [ex-students with] eight [IELTS tests]. I've heard of cases where they've gone into double figures," Mr Bollard said.

To date, the Berenguel ruling is cited by 133 published cases in the tribunal and 10 in the Federal Magistrates Court. The courts have sent more than 30 cases back to the tribunal for rehearing.

Nobody could say exactly how many applications already in the system could be affected.

One reason for uncertainty is disagreement over which visa categories and criteria other than English test results are affected by the High Court's ruling in favour of up-to-date information.

On November 3 in Sydney, a full bench of the Federal Court will hear the minister's appeal in a case called Habib, where a federal magistrate applied the Berenguel rule to a temporary skilled graduate visa.

In effect, the minister argues magistrates have been interpreting Berenguel too liberally in favour of former students. His department said it was "closely monitoring" these decisions.

The minister has not always lost the argument.

In a case called Gill, a former Indian student failed in an attempt to extend Berenguel to a medical test result obtained after his visa application.