International — European Commission & United States — Supreme Court of the United States

International — European Commission: The International — European Commission, led by Ursula von der Leyen, is responsible for the European Union's trade policy and is actively involved in the negotiations and response to the United States' tariff threats.

United States — Supreme Court of the United States: The United States — Supreme Court of the United States ruled in February that Donald Trump had exceeded his authority in imposing a wide swath of tariffs, which complicated the trade situation.

International — European Commission: The International — European Commission rejected Donald Trump's claims of non-compliance and stated it would keep its options open to protect European Union interests. It is actively involved in negotiations and legislative processes related to the trade deal.

United States — Supreme Court of the United States: The United States — Supreme Court of the United States previously ruled that Donald Trump lacked the authority to declare a national emergency to justify many of his tariffs, which complicated the legal basis for the current tariff hike.