OVERSEAS students whose qualifications are being challenged by the commonwealth appear to have won a boost after a migration tribunal overturned a residency visa cancellation.

The tribunal found the department had not given former overseas student Nan Zhang enough opportunity to defend allegations he provided a "bogus" reference to support his skills assessment, and thus residency.

The Department of Immigration and Citizenship alleged he used a bogus job reference to underpin his skills assessment through the federal education department's Trades Recognition Australia, and cancelled his visa. But the tribunal overturned the cancellation -- which would have meant effective deportation -- after finding the contentious documentation provided to TRA did not fall within the Migration Act.

Immigration agent Karl Konrad welcomed the latest Immigration crackdown on the work experience references of former overseas students. "However, despite the warnings to Immigration, potentially tens of thousands of international students between 2001 [and] 2009 didn't have their documents checked thoroughly by TRA or Immigration," he said.

"Even if Immigration now conducts thorough document checks of past students who have already obtained their residency grant, this case highlights there's little they can do if they find bogus documents have been used in the past," Mr Konrad said.

Student rights advocate and Visa Lawyers Australia principal Aristotle Paipetis said the tribunal decision vindicated neither the department nor the student, who must be presumed innocent.

"In my view, before Immigration takes any steps to cancel a person's visa on the basis that fraudulent documents have been provided, the issue needs to have been determined as a matter of criminal law and in a court of law," he said.

The Zhang case revealed that the standard of proof for fraud in a migration context was much lower than acceptable in any other Australian legal context, he said.

An Immigration spokesman said decisions by the tribunal do not set a precedent or affect other cases.