Section 121 of the Constitution Act, 1867

All Articles of the Growth, Produce, or Manufacture of any one of the Provinces shall, from and after the Union, be admitted free into each of the other Provinces.Section 121 is found in Part VIII of the Constitution Act, 1867, dealing with revenues, debts, assets, and taxation.

[8] Although the proceedings of the various conferences were not recorded, George Brown said later that union of all Provinces would "break down all trade barriers between us," and throw open all at once "a combined market of four millions of people."

All Articles the Growth or Produce or Manufacture of Ontario, Quebec, Nova Scotia, or New Brunswick, shall be admitted free into all Ports in Canada.It was subsequently revised in March 1867 into its final form: 121.

All Articles of the Growth, Produce, or Manufacture of any one of the Provinces shall, from and after the Union, be admitted free into each of the other Provinces.As such, it was duly passed as part of the Constitution Act, 1867.

Since 1921, the governing interpretation of s. 121 has come from Gold Seal Ltd. v. Alberta (Attorney-General), which considers that it only bars the levying of customs duties on goods moving between provinces.

I, therefore, reach the conclusion that this legislation is an attempt to impose by indirect taxation and regulations an obstacle to one of the main purposes of Confederation, which was, ultimately, to form an economic unit of all the provinces in British North America with absolute freedom of trade between its constituent parts.

I take s. 121, apart from customs duties, to be aimed against trade regulation which is designed to place fetters upon or raise impediments to or otherwise restrict or limit the free flow of commerce across the Dominion as if provincial boundaries did not exist.

[18] Although customs duties and similar charges are prohibited on this activity, non-tariff barriers can still be instituted by both levels of government, such as:[19] In addition, federal legislation in the following areas has been held to be valid:[20] As a result, there are probably greater obstacles to trade between the provinces than there are to trade between Canada and the rest of the world,[24] and it may explain why Canada has lower productivity than the United States.

[25] There has been debate as to whether Gold Seal would continue to hold under the current Canadian practice for constitutional analysis, most notably in the following areas:[26] It is therefore argued that, under a purposive interpretation such as Rand J. had proposed, s. 121 requires any federal or provincial statute to meet three requirements:[27] This proposition has not yet been tested, but it has been suggested that the Importation of Intoxicating Liquors Act could be found to be unconstitutional as a result.

[29][30] In April 2016, the trial judge invalidated the provisions, declaring, "That historical context leads to only one conclusion: The Fathers of Confederation wanted to implement free trade as between the provinces of the newly formed Canada.