Lawyer Matt Webber, right, photographed in 2006 with his client Mohamed Harkat, centre, says he was was flabbergasted to learn CSIS monitored conversations between defence lawyers and terrorism suspects. (Tom Hanson/Canadian Press)

Canada's spy service has ceased listening in on telephone calls between lawyers and suspected foreign terrorists detained under national security certificates in light of a judge's ruling in one of four such cases, an agency spokesman said Tuesday.

It will be up to each judge presiding over Canada's other security certificate cases to formally decide whether the service can resume tapping such solicitor-client calls, said John Dunn, who is with the Canadian Security Intelligence Service (CSIS).

Last Friday, Federal Court ordered an end to the monitoring of phone conversations between Mohammad Mahjoub, an Egyptian accused of having been part of an organization with close ties to al-Qaeda, and his lawyers.

Mahjoub is one of five Muslim men under a national security certificate as potential threats to public safety.

He and three others have been released on stringent bail conditions, including their consenting to having all their phone calls monitored.

"We were doing this surveillance in the first place because a court ordered it," Dunn said from Ottawa.

"So when the court clarified [its order], we of course followed the court's order, but we also changed our practices at that point in the security certificate cases."

Mahjoub's lawyers incensed

The issue erupted after a secret hearing in Ottawa last week in which a senior security agent revealed the spy agency had been tapping Mahjoub's phone calls — even those with his lawyers.

The revelation incensed lawyers for Mahjoub and the other three suspects.

They argued their clients' consent to phone monitoring never included agreeing to having calls with their lawyers tapped, noting the right to confidentiality between lawyer and client is sacrosanct under the Constitution.

A government official suggested the conflicting point of view was based on a different understanding of what had been consented to.

"We did assume that it was all communications," a government official, who asked not to be identified, said Tuesday.

"I guess on the other side, it was assumed it didn't include all communications but on our side it was [assumed it did]."

Court amended bail orders

In light of Mahjoub's lawyers' objections, Federal Court specifically amended his bail orders to exclude further monitoring of calls with his lawyers.

CSIS is doing the phone tapping at the request of the Canada Border Services Agency, which is charged with ensuring the men adhere to their rigid bail conditions.

The border agency lacks the expertise to do the surveillance, which is why the spy service is doing the monitoring.