Public Safety Minister Bill Blair says Ottawa is appealing a court ruling that struck down the Safe Third Country Agreement on refugees between Canada and the United States.
The Federal Court of Canada ruled last month that elements of the law underpinning the pact violate the constitutional guarantee of life, liberty and security.
The declaration of invalidity was suspended for six months, leaving the law in place until mid-January.
Under the agreement, which took effect in 2004, Canada and the U.S. recognize each other as safe places to seek protection.
It means Canada can turn back potential refugees who arrive at land ports of entry along the Canada-U.S. border on the basis they must pursue their claims in the U.S., the country where they first arrived.
In a statement, Blair says there are factual and legal errors in some of the Federal Court's key findings, and the government wants to ensure clarity on the legal framework governing asylum law.