The Supreme Court of Canada has struck down a law that allows police to tap telephones without a warrant in an emergency.

In its ruling, the court said that Section 184.4 "falls down on the matter of accountability" because the existing structure doesn't provide a framework for oversight of police actions.

"Of particular concern, it does not require that notice be given to persons whose private communications have been intercepted," the Supreme Court said.

The judges found the section in its present form to be unconstitutional, and said Parliament should be given 12 months to rewrite the law.

Although the court has found Section 184.4 is unconstitutional, police could still make use of this provision until Parliament rewrites the law. However, a judge would have to be convinced to admit any evidence gathered in this way.

A statement issued by the office of Justice Minister Rob Nicholson said the government would review the "decision carefully to determine next steps."

Kidnapping case prompted ruling

The ruling stems from a case that reached the high court after the conviction of six men in a kidnapping in British Columbia.

Peter Li, his then girlfriend Jennifer Pan, and his friend Xiao Cheng were kidnapped in Burnaby in February 2006.

Police intercepted communications without a warrant because they feared for the lives of the kidnapping victims. Police later went to a judge to get authorization for ongoing interceptions.

The CBC's Alison Crawford said there are other provisions in the Criminal Code that deal with wiretapping, and they require police to report to Parliament every year how many times they've used that power. Those provisions also require police to notify people whose phones have been tapped.

In the B.C. kidnapping case, a provincial Supreme Court judge sentenced the men to prison terms ranging from 10 to 18 years. At trial, the judge ruled the police violated the Charter of Rights and Freedoms, but admitted the wiretap evidence anyway.

Friday's ruling will not change the verdicts in the kidnapping case. However, individuals who were convicted have filed separate appeals that are making their way through the courts.