In 1991, celebrations were planned to mark the bicentennial of the first meeting of the legislature of Upper Canada at Newark (Niagara-on-the-Lake) on September 17, 1792. This presented an opportunity for the Legislative Assembly to assert symbolically its independence from the Government that is formalized in the Legislative Assembly Act.
A petition was made by the then-Speaker, David Warner, to the Chief Herald of Canada for the granting of a unique Coat of Arms which would emphasize the distinctive character of the Legislative Assembly and to distinguish the Assembly's identity from the Government. To that point, the Assembly had used the Coat of Arms of the Government of Ontario.
The petition was granted and the new Coat of Arms was presented by Governor-General Ramon Hnatyshyn at a ceremony in the Legislative Chamber on April 26, 1993. The Legislative Assembly of Ontario is the first legislature in Canada to have a Coat of Arms separate from the provincial coat of arms.
Green and gold are the principal colours in the shield of arms of the province. The Mace is the traditional symbol of the authority of the Speaker. Shown on the left is the current Mace. On the right is the original Mace from the time of the first parliament in 1792. The crossed Maces are joined by the shield of arms of Ontario.
The crown on the wreath represents national and provincial loyalties; its rim is studded with the provincial gemstone, the amethyst. The griffin, an ancient symbol of justice and equity, holds a calumet which symbolizes the meeting of spirit and discussion that Ontario's First Peoples believe accompanies the use of the pipe.
The deer represent the natural riches of the province. The Loyalist coronets at their necks honour the original European settlers in Ontario who brought with them the parliamentary form of government. The Royal Crowns, left 1992, right 1792, recognize the parliamentary bicentennial and recall our heritage as a constitutional monarchy. They were granted as a special honour by Her Majesty Queen Elizabeth II on the recommendation of the Governor General.
In the base, the maple leaves are for Canada, the trilliums for Ontario and the roses for York (now Toronto), the provincial capital.
The motto "AUDI ALTERAM PARTEM" is one of a series of Latin phrases carved in the Chamber of the Legislative Building. It challenges Members of Provincial Parliament to "Hear the Other Side".