In IHL, neutrality describes the position taken by States to abstain from participating in an armed conflict. Neutrality entails certain duties: the duty not to participate in an armed conflict; the duty of impartiality vis-à-vis belligerents; and the duty to resist violations of neutrality (in sum: the duties of abstention, impartiality and prevention). Neutrality also gives rise to rights, with the main one being the inviolability of the neutral's territory. If troops belonging to the belligerents are found on the territory of a neutral State they should be interned. If a neutral State breaches one of its duties it forfeits its rights as neutral and the belligerents may take measures against that State. Which acts cause the loss of neutrality and whether the State in this case becomes a belligerent are subject to debate. The changing nature of armed conflict, in particular cyber war, challenges the traditional concept of neutrality as does the UN collective security system and diverse military alliances.
Resources: Arts 1–17, HCV; Arts 6–24, Hague Convention XIII (HCXIII); Arts 4, 19, 22, 23, 47, GCI; Art. 5, GCII; Arts 4, 109–111, GCIII; Art. 4, GCIV; Arts 2, 19, 47, API; Arts 2(5), 39–42, 103, UN Charter
DEFINITION OF NEUTRALITY; RIGHTS AND DUTIES OF NEUTRALS
US Supreme Court, The Santissima Trinidad, 20 U.S. 283 (1822), pp. 337–8
Note: The case arises in the context of the civil war between Spain and her colonies. The United States recognised them as belligerents. The Neutrality Act of 1794 provided for the nation's impartiality and prohibited its citizens from assisting the belligerents but US citizens violated the Act. In 1817, the Consul of Spain filed a libel claim in the District Court of Virginia in relation to the seizure of goods from the ship The Santissima Trinidad. As to the principle of neutrality and the duties incumbent on a neutral State, the US Supreme Court said as follows:
The government of the United States has recognized the existence of a civil war between Spain and her colonies, and has avowed a determination to remain neutral between the parties, and to allow to each the same rights of asylum and hospitality and intercourse.