He also holds the title of Adjunct Professor of International Law at the University of Helsinki, where he is affiliated with the Erik Castrén Institute of International Law and Human Rights. Rain's current research focuses on the legal and ethical challenges associated with the military applications of science and technology generally and biosciences specifically. His broader research and teaching interest include the law of armed conflict, human rights law and the law of treaties, as well as international and comparative criminal law. Rain serves as a member of the Board of Directors of the International Society for Military Law and the Law of War, and as a Council member of the Australian and New Zealand Society of International Law.