A fundamental principle in International Law is the concept of Jus cogens rules. These are peremptory norms that are accepted and recognized by the international community of states as a whole, from which no derogation is permitted. In other words, these rules are so fundamental that they bind all states universally and do not allow any exceptions or agreements to the contrary.
Examples of Jus cogens norms include the prohibition of genocide, slavery, torture, and crimes against humanity. These norms override any conflicting treaty or customary international law.
The concept of Jus cogens ensures that certain basic principles of human rights and international conduct are upheld regardless of individual state consent, maintaining a minimum standard of international behavior.
Thus, the correct answer to the question is Jus cogens rule, as it is a binding norm in International Law with no exceptions.
Conclusion:
Jus cogens rules represent non-derogable principles that uphold the core values and order of the international legal system, ensuring universal compliance by all states.