How true is it to say that the rules of International law would not exist without the consent of states?

Question

I've read about express consent somewhere. If a state has not given consent to be bound by a rule or principle of international law it cannot exist. How true is this?

States for the purposes of International Law can be considered as countries, nations etc... I am not referring to the United States

Answer 1

I think the asker meant Capital-S States, not the states of the US.

States need not consent to be affected by treaties others have agreed to.

It is a fair bet N Korea has not consented to the sanctions it has been living under as enforced by most if not all of the world.

Answer 2

Well, not quite. It wouldn't exist except for the consent of the COUNTRIES, not the states. Of particular importance are the Hague Convention and the Geneva Convention.