By Gib van Ert, Robert J. Currie and Allan Rock
March 26, 2025
BURLINGTON, ON
Originally published on Policy Options
Late in 2024, the incoming president of the United States, Donald Trump, began calling for the annexation of Canada.
What was first taken as a tasteless joke quickly emerged as a chief plank of the new administration’s foreign policy. On Jan. 7, a reporter asked Trump whether he intended to use military force against Canada – something he had threatened only moments earlier to use against Panama and Greenland. “No, economic force,” Trump replied.
Both military and economic force to annex another country are forbidden under Canadian and international law. Any U.S. takeover attempt already faces serious political and public resistance. But we also have legal and constitutional defences of our sovereignty, to be taken up if needed. Let us hope it does not come to that. But lawyers and judges must be ready in case it does.
Trump’s goal is clear
Trump repeated his commitment to territorial aggrandizement in his inaugural address, saying: “The United States will once again consider itself a growing nation, one that increases our wealth, expands our territory, builds our cities, raises our expectations and carries our flag into new and beautiful horizons.”
Since becoming president on Jan. 20, Trump has followed through with his threats in the form of on-again, off-again tariffs on various Canadian exports designed to cause severe damage to our economy.
He uses nonsensical justifications for tariffs, but his real goal is clear – the use of economic force to undermine Canadian sovereignty and pave the way for U.S. annexation.
Trump repeated his commitment to territorial aggrandizement in his inaugural address, saying: “The United States will once again consider itself a growing nation, one that increases our wealth, expands our territory, builds our cities, raises our expectations and carries our flag into new and beautiful horizons.”
He also invoked Manifest Destiny, the discredited 19th-century American belief in the irresistible spread of its empire across North America.
International law is on Canada’s side
The acquisition of territory by force has been illegal under international law since the end of the Second World War – ironically because of U.S. leadership at the San Francisco conference that drafted the 1945 United Nations Charter.
Article 2(4) requires all UN members to “refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state.”
The UN Declaration on Principles of International Law Concerning Friendly Relations and Co-Operation Among States affirms that no acquisition of territory by “the threat or use of force shall be recognized as legal” and no state may use “economic, political or any other type of measures to coerce another state in order to obtain from it the subordination of its exercise of its sovereign rights.”
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This prohibition is also a matter of international human-rights law, specifically the right to self-determination. Of particular importance to Canada, Article 3 of the UN Declaration on the Rights of Indigenous Peoples specifically confirms the right of Indigenous Peoples to “freely determine their political status.”
These international norms are also part of Canadian law. They represent customary international law, which the Supreme Court of Canada has repeatedly affirmed forms part of Canadian common law.
This means that the international legal principles of Canadian sovereignty over its territory, the right of Canadians to self-determination and the illegality of foreign acquisition of territory by threat or use of force, including economic force, are rules of Canadian common law that must, in proper cases, be given effect by Canadian judges.
The Constitution assumes Canadian sovereignty
Canadian sovereignty and territorial integrity also underpin our written Constitution. The Constitution Act, 1867 (formerly the British North America Act) vests executive power in the Sovereign, establishes a Privy Council for Canada and continues the command-in-chief of Canada’s land and naval forces in the Sovereign as head of state.
These provisions are irreconcilable with any transfer of executive power from the head of state, as advised by Canadian political leaders, to a foreign power.
Major amendments to the Constitution in 1982 added the Canadian Charter of Rights and Freedoms, the protection of Aboriginal rights and a new mechanism for amending the Constitution without British involvement. Throughout its provisions, the Constitution Act, 1982 assumes, and requires, Canadian independence.
Section 3 confirms the rights of all Canadian citizens to vote in elections for members of the House of Commons and to serve as MPs. The continued existence of the Commons as the elective element of our federal legislature is the essential prerequisite of these rights.
Section 6 declares the right of every Canadian citizen to enter, remain in and leave Canada – a meaningless right without a Canada to enter, remain in and leave.
Part V sets out several ways in which the Constitution can be amended. Capitulation to a foreign power is not one of them.
Finally, Section 52(1) provides that the Constitution is the supreme law of Canada and that any law inconsistent with it is of no force or effect. The force of all the Constitution’s other provisions turns on this one, which empowers Canadian courts to strike down other laws as unconstitutional.
Indigenous rights are also critical
The position of Canada’s Indigenous peoples must also be remembered.
Modern Canada is the product of a series of territorial encroachments and acquisitions by France and Britain in pre-modern times. Canadian courts continue to struggle with the consequences of that history, empowered by the 1982 Constitution’s recognition and affirmation in Section 35 of the existing Aboriginal and treaty rights of the Aboriginal peoples of Canada.
This process of reconciliation gained new impetus with Canada’s adherence to the UN Declaration on the Rights of Indigenous Peoples in 2016 and Parliament’s recognition of that declaration as a universal international human-rights instrument with application in Canadian law.
All of this gives legal foundation to an instinct that should come naturally to anyone living on this continent: we are long past the point in our history where Indigenous lands and traditional territories can be swapped back and forth between states without Indigenous consent.
Judicial resistance may be needed
The United States seems now to have turned against the principles it once championed. But those principles remain the foundation of both the international legal order and Canada’s laws.
American attempts to force annexation by economic means are being met with strong resistance from our political leaders and the public. That resistance may succeed and Trump’s dream of making Canada the 51st state may be shattered by politics alone.
But if Canada-U.S. relations so deteriorate that our independence is actively threatened, political and popular resistance may require the support of legal and judicial resistance. The annexation of Canada by a foreign power is manifestly illegal. Canada’s courts must not hesitate to say so.
Gib van Ert is a partner at Olthius van Ert and a former president of the Canadian Council on International Law.
Robert J. Currie, K.C., is the Viscount Bennett Professor of Law in the Schulich School of Law at Dalhousie University.
Allan Rock is president emeritus of the University of Ottawa. He has served as federal minister of justice and attorney general, as well as Canadian ambassador to the United Nations.
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