UN Security Council Resolution 1540 requires all UN member states to impose effective measures against chemical, nuclear or biological weapons, their means of delivery or their related materials by non-state actors. It also includes measures to prevent the proliferation of chemical, nuclear or biological weapons. A contract is null and void if it violates a mandatory standard. Unlike other principles of customary law, these standards are not recognized as offences and therefore cannot be changed by contractual obligations. These are limited to prohibitions as universal as those against the aggressive use of force, genocide and other crimes against humanity, piracy, hostilities against the civilian population, racial discrimination and apartheid, slavery and torture, meaning that no state can legally commit to commit or admit such acts.  When a state limits its contractual obligations by reservations, other contracting states have the opportunity to accept, oppose or oppose these reservations. If the state accepts (or does not act at all), both the reserve state and the accepting state are exempt from the legal obligation reserved with respect to their legal obligations with each other (the acceptance of the reservation does not alter the legal obligations of the accepting state with respect to the other contracting parties). If the state objects, the parts of the contract concerned by the booking are completely cancelled and no longer create legal obligations for the reserve and acceptance of the state, again only with regard to the other. Finally, if the state opposes and opposes it, there are no legal obligations arising from this treaty between these two states. The resisting and reticating state essentially refuses to recognize the reserving state, is even a party to the treaty.  The Tribunal found that treaties are subject to constitutional control and occupy the same hierarchical position as ordinary legislation (leis ordinrias, or “ordinary laws,” in Portuguese).