war
n. The legal state of affairs that exists when states use force to vindicate rights or settle disputes between themselves. States can engage in hostilities (e.g. reprisals) without being in a technical state of war, and they can be in a state of war without much fighting taking place. At common law a state of war could not exist until there had been a formal declaration of war or commencement of hostilities by the Crown. The legal condition of war automatically terminates diplomatic relations and certain types of treaties between the participants. Normal intercourse and commerce between British subjects and those of a power with which the Crown is at war are prohibited.

In the Kellogg–Briand Pact (also known as the Pact of Paris) of 1928, the contracting parties renounced war as an instrument of national policy and undertook to settle their disputes by peaceful means. The United Nations Charter declares that all parties to it “shall refrain…from the threat or use of force against the territorial integrity or political independence of any state” or in a manner inconsistent with the Charter, and this is commonly accepted as an accurate statement of customary international law. Nonetheless it appears that states still retain a right of self-defence, at least if they have been the victims of armed attack and until the Security Council can act. The Security Council is also authorized to use force (or to call upon states to do so) under certain circumstances in order to protect the peace, although in practice this power has not been invoked (see use of force). The right of self-defence includes a collective right to assist other states acting in self-defence.

The Hague Conventions and Geneva Conventions provide rules governing the conduct of wars and stating the rights and duties of both combatants and noncombatants during war. However, they do not deal with all aspects of warfare or all types of war. There have also been various specific conventions governing particular issues, including a 1972 convention on the use or possession of bacteriological and toxic weapons, a 1976 convention on the military use of environmental modification techniques, and a 1981 convention and three protocols on cruel or indiscriminate non-nuclear weapons. Civil wars are not usually illegal from the point of view of international law, but it is uncertain whether or not other states may legally help either the insurgents or the established authorities (see belligerent communities, recognition of; insurgency). The 1977 First and Second Protocols to the Geneva Conventions of 1949, respectively, extend some of the laws of war to civil wars and wars of national liberation (see self-determination).

See also aggression; humanitarian intervention; martens clause; occupation; offences against international law and order; war crimes.

• age of consent
• aggravated assault
• aggravated burglary
• aggravated damages
• aggravated trespass
• aggravated vehicle-taking
• aggregates levy
• aggression
• agreement
• agreement for a lease
• agricultural holding
• Agricultural Land and Drainage
• agricultural property relief
• agrément
• aid and abet
• Air Defence Identification Zone
• air force law
• air pollution
• air rage
• airspace
• alcohol treatment requirement
• alderman
• aleatory contract
• alibi
• alien