Final answer:
A country can ignore criticism from the United Nations on their use of capital punishment by invoking the principle of state sovereignty, which grants them the authority to govern themselves and make independent decisions.
Step-by-step explanation:
A country that has been criticised by the United Nations for using capital punishment may choose to ignore this criticism based on the principle of state sovereignty. State sovereignty is the concept that states are in complete and exclusive control of all the people and property within their territory. It gives them the authority to govern themselves independently and make decisions, including those about capital punishment, without external interference. The International Court of Justice also does not have jurisdiction in capital punishment cases that involve foreign nationals according to Breard v. Greene. This principle is recognized under international law and often poses a challenge for the global community, especially when it comes to the protection of human rights. However, while sovereignty grants this power, it can come into conflict with the international norms of human rights as enshrined in the United Nations Universal Declaration of Human Rights.