The Ontario Heritage Act came into force in 1975:
The Government Efficiency Act came into force on November 26, 2002. It included changes to the Ontario Heritage Act to clarify, update and streamline its provisions related to archaeology and built heritage protection.
These changes were an interim measure. In 2005, the government passed comprehensive amendments to the Ontario Heritage Act. These amendments modified those made in the Government Efficiency Act. They strengthen and improve heritage protection in Ontario, bring Ontario's heritage legislation in line with leading jurisdictions in Canada and: