What International Law Principle Guarantees Fundamental Rights for Everyone?

The principle of international law that ensures fundamental rights for all individuals, regardless of their nationality or legal status is 'Human rights law' (D).

Human rights law encompasses a body of international law that recognizes and protects fundamental rights inherent to all human beings. It aims to ensure that everyone, regardless of their background, enjoys essential rights such as the right to life, liberty, and security of person; freedom from torture and cruel, inhuman, or degrading treatment; and the right to a fair trial.