The Canadian government revoked citizenship for many recent applicants encouraged by a weakened ancestry rule, after many were accepted despite insufficient documentation.

Canada has long held that citizenship by descent only extends to the first generation, those born abroad to Canadian parents. People born to second-generation Canadians were traditionally excluded, but a recent amendment to the country’s Citizenship Act broadened citizenship-by-ancestry to ensuing generations. Thousands of these so-called “Lost Canadians” applied for citizenship under the new rules after they took effect in December, and many were granted. On Saturday, an unknown but significant number of these received letters or emails from the Canadian government, demanding the return of their citizenship certificate.