The high court also rejected Harkat's constitutional challenge of the security certificate regime, unanimously ruling the process is consistent with the Charter of Rights and Freedoms.
Harkat, 45, was taken into custody in Ottawa in December 2002 on suspicion of being an al-Qaida sleeper agent — an accusation he denies.
The federal government is trying to deport the Algerian refugee on a security certificate — a seldom-used tool for removing non-citizens suspected of involvement in terrorism.
Harkat's lawyers argued the process was unfair because the person named in a certificate doesn't see the full case against them.
The Supreme Court says the security certificate regime does not violate the person's right to know and challenge the allegations they face.
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