Statutes can delegate the president tariff powers and appropriately circumscribe them, and that's what both the IEEPA and Trade Expansion Act did - they gave the executive tariff authority in certain circumstances.

Trump is stretching the definition of those circumstances to the limit, in my opinion, especially because protectionism is the fundamental policy being pursued. If we want general protectionist tariffs than the law should be passed that enables the executive to do so, but that hasn't been forthcoming.

How effective are tariffs as a trade negotiation tool if your counterparty believes its likely the courts will take away the big stick?