Can citizenship be revoked from someone who has already held it for decades?

Yes. There is no time limit that protects citizenship from revocation once fraud or misrepresentation in how it was originally granted is established, even if it is discovered decades after the fact. How long someone has held citizenship, on its own, does not prevent revocation proceedings from being brought, since the basis for revocation is the integrity of the original grant, not how much time has since passed.

This can come as a significant shock to long-term citizens who assume that decades of settled life in Canada, including things like working, raising a family, or building a career here, would insulate them from this kind of proceeding. In practice, the length of time someone has held citizenship can be a relevant factor considered within the broader revocation process, but it is not, by itself, a legal bar to revocation being pursued at all.

Anyone facing a revocation proceeding after holding citizenship for a long time should not assume the passage of time alone will resolve the matter, and should seek experienced legal representation promptly given how serious and consequential a revocation finding can be.