Русско-англо-русский юридический словарь

The head of state is the highest-ranking constitutional position[note 1] in a sovereign state. The head of state is vested with powers to act as the chief public representative of that state. Heads of state in most countries are natural persons holding an office. In a monarchy the reigning monarch is the head of state, though the title may not be king or queen. In a republic the head of state is usually titled president, but may have other titles such as chairman. (Wikipedia)

Amnesty (from the Greek ἀμνηστία amnestia (Amnesty, Wm Chrichton Μεγα Ελληνο-Αγγλικον Λεξικον 1960) is defined as: "A pardon extended by the government to a group or class of persons, usually for a political offense; the act of a sovereign power officially forgiving certain classes of persons who are subject to trial but have not yet been convicted." (Wikipedia)

International Relations (IR) is the study of relationships among countries, the roles of sovereign states, inter-governmental organizations (IGO), international non-governmental organizations (INGO), non-governmental organizations (NGO), and multinational corporations (MNC). International relations is an academic and a public policy field, and so can be positive and normative, because it analyzes and formulates the foreign policy of a given State. (Wikipedia)

A treaty is an agreement under international law entered into by actors in international law, namely sovereign states and international organizations. A treaty may also be known as an (international) agreement, protocol, covenant, convention, pact, or exchange of letters, among other terms. Regardless of terminology, all of these forms of agreements are, under international law, equally considered treaties and the rules are the same. (Wikipedia)