The British Columbia Terms of Union is the document that caused the province of British Columbia to become a part of the country of Canada, when it had formerly been a British colony. Since the Terms of Union existed prior to BC existing as a province, copies of the Terms can be a little tricky to locate in official government publications.
The BC Terms of Union can be found in a special BC Statutes Appendix volume published in 1871. In CLBC’s collection it is indexed with the call number KP21.L38 1871 v. 2.
It can also be found in the British Columbia Gazette from 1871 which has the call number KP39.
The Terms of Union can be located online on the Department of Justice website.
An associated piece of legislation that covered British Columbia becoming subject to Canadian law after joining the country can be located in the Statutes of Canada 1871, called “An Act respecting the force and effect of the Acts of the Parliament of Canada, in and in relation to the Province of Manitoba, and the Colony of British Columbia when it becomes a Province of the Dominion.” It is indexed in CLBC’s collection with the call number KP2.S7 1871.