International and Public Law
Public international law
Know the sources: treaties, custom, general principles, and judicial decisions. Understand the law of treaties (formation, reservation, interpretation, termination), state responsibility, and the rules on the use of force (self-defense, Security Council authorization). Trap: customary international law binds all states; a treaty binds only parties unless it codifies custom.
Human rights and humanitarian law
Know the core human rights instruments, the distinction between international human rights law and international humanitarian law, and the rules on occupation and protected persons.
Worked rule of thumb
For any international law question: (1) is the norm treaty or custom; (2) is the state bound; (3) is there a breach and an attribution; (4) what is the remedy or countermeasure?