In what year were internment camps closed in Canada, and not used again since that date?

Internment is the confinement of a person during war. In Canada, such persons were denied certain legal rights, notably habeas corpus. Even if they were not strictly Prisoners of War, civilian internees were generally treated according to international prisoner of war standards.

During WW I, enemy aliens (nationals of Germany and of the Austro-Hungarian and Turkish empires) were interned, but only if there were "reasonable grounds" to believe they were engaged in espionage or otherwise acting illegally.

In 1916–17, many Austrians were paroled to fill labour shortages. Of 8,579 men at 24 camps across Canada, the majority were Ukrainian, but also included Austro-Hungarians, Germans, Turks, and Bulgarians. All endured hunger and forced labour, helping to build some of Canada's best-known landmarks, such as Banff National Park. Moreover, 237 women and children, dependants of male internees, were voluntarily interned themselves.

During WW II, the Minister of Justice could detain anyone acting "in any manner prejudicial to the public safety or the safety of the state." Thus both enemy nationals and Canadian citizens were subject to internment. Around 40 camps held approximately 32,500 prisoners. Approximately 20,000 Japanese Canadians were interned in 1942. Many of these internees were held until 1949, four years after World War II ended. Once they were released, the camps were closed and have not been used again.