Which government agencies handled any refusal of U.S. milk entering Canada?

1. Canadian health-and-inspection enforcement: the CFIA and import rules

Operational refusals at the border or during import clearance fall under Canada’s food and animal-health regulatory framework, administered by the Canadian Food Inspection Agency (CFIA), which enforces the Health of Animals Act restrictions on milk products from countries or products that could introduce animal diseases such as foot-and-mouth disease and requires export/import documentation like zoosanitary certificates ^{[1] [2]}.

2. Canadian quota and allocation authorities: TRQs, the CDC and provincial milk boards

Beyond on‑farm and border health rules, Canada’s system of tariff‑rate quotas and supply management—structured around the Canadian Dairy Commission (CDC), provincial milk boards and quota allocation mechanisms—effectively controls how much foreign milk and dairy product can enter and who may use quota allocations, a policy lever that can result in U.S. milk being excluded in practice even when a TRQ exists ^{[5] [6] [7]}.

3. U.S. trade enforcement: USTR and USDA pushing disputes over access

When access for U.S. dairy producers is denied or impeded by Canada’s TRQ allocation measures, the U.S. has responded with trade‑dispute tools: the Office of the U.S. Trade Representative (USTR) has led USMCA challenges and public announcements asserting that Canada reserved in‑quota volumes for domestic processors, and USTR officials have worked closely with the U.S. Department of Agriculture (USDA) to seek compliance ^{[3] [8] [9]}.

4. Foreign Agricultural Service, industry and diplomatic pressure

The USDA’s Foreign Agricultural Service (FAS) plays an informational and diplomatic role in Washington‑Ottawa trade questions, advising exporters and sometimes supporting USTR/USDA actions; U.S. industry groups and Congressional allies have amplified those trade actions, framing quota allocation as a barrier that results in effective refusals of U.S. dairy access ^{[4] [6] [10]}.

5. Legal and multilateral channels: WTO and USMCA adjudication

Longstanding disagreements over Canadian dairy policy have also been litigated at multilateral fora: the WTO’s dispute settlement history shows earlier U.S. challenges to Canadian milk‑and‑quota administration, and USMCA panels have been used more recently to adjudicate claims about TRQ allocation and implementation—mechanisms the U.S. has used when it regards Canadian administration as tantamount to refusing market access ^{[11] [3] [9]}.

6. Perspectives, incentives and what the sources do not show

The public record makes clear competing incentives: Canadian authorities and the CDC emphasize supply management and disease control to protect domestic producers, while U.S. trade agencies and dairy groups press for fuller market access—an adversarial dynamic that explains both border enforcement and trade litigation ^{[5] [10]}. The available reporting does not provide case‑level customs paperwork or name other specific Canadian operational agencies that physically turned away shipments, so this account cannot assert which frontline customs officers or exact offices executed any particular shipment refusal beyond CFIA’s regulatory mandate and quota administration structures ^{[1] [2] [12]}.

7. Bottom line: who “handled” refusals

In practice, refusals of U.S. milk into Canada have been handled on the Canadian side by the CFIA administering health and import rules and by Canada’s quota and supply‑management apparatus (CDC and provincial boards) that allocate TRQ access; on the U.S. side, denials or constrained access have been contested and escalated by trade agencies—principally USTR with USDA/FAS support—through USMCA and other dispute channels ^{[1] [2] [5] [3] [4] [9]}.