The law -- dubbed Lex Brunner after its instigator, far-right SVP leader Toni Brunner -- was introduced in January last year to prevent asylum seekers from abusing the system and getting around rejections of their asylum applications by marrying Swiss nationals.
The problem with the new law is that it may infringe the human right to marry under the European Convention on Human Rights, newspaper Tages Anzeiger reported on Wednesday.
As a result of this discrepancy, certain cantons have started granting illegal immigrants the right to marry Swiss citizens.
In Bern and Vaud, for example, illegal immigrants with criminal records have been given the green light to wed in direct contravention of the law.
But a recent case in Zurich may lead to the re-establishment of the marriage rules.
In 2008, a young man entered the country illegally. His application for asylum was rejected and he was given until August 2010 to leave the country.
He failed to do so and recently requested permission to marry a Swiss woman.
His request was turned down and he appealed to the Department of Justice, which supported his appeal in part and instructed the registry office to review the pair’s application.
However, in order to prevent the law being set aside as it has been in the other cantons, the Federal Office of Justice has submitted the case to the cantonal administrative court.
This court has no discretion in its interpretation of the rules, which will mean that if the foreign fiancé is unable to present evidence of his legal residency in Switzerland, he will be refused permission to marry.