Military aid to the civil power

Military aid to the civil power (MACP) (sometimes to the civil authorities) is a term used to describe the use of the armed forces in support of the civil authorities of a state. The term is used in many countries, with slightly different definitions and implications in each.

Australia
In Australia, there are two forms of aid the Australian Defence Force can provide to the civil power, further divided into a range of categories.

Defence Assistance to the Civil Community (DACC)
 * DACC Category 1: Assistance in local emergency situations when immediate action is necessary to save life. This can be arranged at the local level between civilian emergency services and local ADF commanders.
 * DACC Category 2: Emergency assistance in more extensive or continuing disaster when State or Territory resources are inadequate. This may include search and rescue, transport and evacuation, and communications. Requests for such assistance are normally made by State or Territory governments to the Federal Government. Examples of this included large scale assistance after the 1955 Hunter Valley floods, Cyclone Tracy, 1989 Newcastle earthquake, Black Saturday bushfires and 2011 Queensland floods.
 * DACC Category 3: Assistance in recovery from an emergency or disaster which is not directly related to the saving of life or property. Requests for such assistance are normally made by civilian emergency services through Emergency Management Australia. This includes, for example, providing temporary bridges where permanent bridges have been destroyed by fire or flooding.
 * DACC Category 4: Non-emergency assistance for public relations and ceremonial purposes. This includes requests for ADF equipment for use in film and television productions, flypasts for public events and performances by military bands. Requests for such assistance are normally made by the organiser through Department of Defence Public Affairs.
 * DACC Category 5: Non-emergency assistance of a minor nature. This includes training for emergencies and disasters and other forms of training, except training with law enforcement.
 * DACC Category 6: Support to civil authorities in the performance of non-emergency law enforcement where there is no possibility of the ADF using force.

Defence Force Aid to the Civil Power (DACP)

This involves the use of the Australian Defence Force to assist with law enforcement. State or Territory law enforcement has primary responsibility for law and order. Under section 119 of the Constitution of Australia, "The Commonwealth shall protect every State against invasion and, on the application of the Executive Government of the State, against domestic violence." This is further explained in section 51 of the Defence Act which states that: "Where the Governor of a State has proclaimed that domestic violence exists therein, the Governor-General, upon the application of the Executive Government of the State, may, by proclamation, declare that domestic violence exists in that State, and may call out the Permanent Forces and in the event of their numbers being insufficient may also call out such of the Emergency Forces and the Reserve Forces as may be necessary for the protection of that State, and the services of the Forces so called out may be utilised accordingly for the protection of that State against domestic violence."

Military forces have been deployed three times on the request of State or Territory governments:
 * September 1970: The Governor-General signed an Order-in-Council authorising the deployment of the Army to East New Britain Province of Papua New Guinea, then a territory of Australia, to assist local police with riot control if necessary. The Army was not required and the Order was revoked in April 1971.
 * February 1978: Following the Sydney Hilton bombing, 2,000 armed soldiers were deployed to Bowral and Mittagong to protect the Commonwealth Heads of Government Regional Meeting and to protect the road and rail links between Sydney and the Southern Highlands.
 * March 2002: 2,400 military personnel were deployed to protect the Commonwealth Heads of Government Meeting at Coolum Beach, Queensland, including armed F/A-18 Hornets patrolling overhead, just months after the September 11 terrorist attacks.

Australian Military Regulations also allow the Federal government to use military forces "on its own initiative, for the protection of its servants or property, or the safeguarding of its interests". This has been done three times:
 * April 1983: RF-111C reconnaissance aircraft were used to investigate construction work by the Government of Tasmania which was preparing to dam the Gordon River in contravention of federal law. The evidence from the reconnaissance flights was used to gain an injunction from the High Court of Australia against the work.
 * September 1989: Soldiers were deployed to Joint Defense Facility Nurrungar during a large political demonstration in which 300 protesters broke through the perimeter fence.
 * August 2001: The Special Air Service Regiment was used during the Tampa affair.

In addition, unarmed troops and defence force equipment has been used in industrial disputes, such as the 1949 Australian coal strike and the 1989 Australian pilots' dispute, under the "safeguarding of its interests" provisions.

Canada
Canada has provisions similar to the UK (see below) for military aid to the civil power inscribed in its National Defence Act, an historical inheritance from its days as a British dominion. However, the application is significantly different due to the federal nature of Canada, where the maintenance of "law and order" is the exclusive right and responsibility of the provinces.

The political authority empowered to requisition military aid is therefore the Solicitor General of the affected province, which was provided for under the War Measures Act and currently the Emergencies Act. This request is forwarded directly to the Chief of the Defence Staff (not to the federal government of Canada) who is obliged by law to execute the request. However, the Chief of the Defence Staff alone can determine the nature and level of forces to be committed.

The requesting province may subsequently be billed to pay the cost of the military aid, although the federal government, which does not want to appear "cheap" after a major crisis affecting a province, most often waives it. One exception in recent years resulted from Toronto mayor Mel Lastman's request for military assistance following a snow storm in 1999, whereby 300 reservists were activated to assist in snow removal after the Ontario government acceded; this deployment was deemed by the Canadian government to be a trivialization of the military's emergency response role and the requesting authority was billed accordingly.

While the military is legally free to decide how to deal with an issue in regard to which it has been called out, in practice it works under the direction of the police forces or government of the province that has requested its aid. Such requests are made relatively often for specialized resources such as armoured vehicles (e.g. hostage situations) and technical capabilities not possessed by police forces.

They are also called out in the case of police strikes in those provinces that have unionised provincial police forces. Quebec has not hesitated to call on the Army for such help because the Army is the only other agency with French speaking members able to replace striking police; the Royal Canadian Mounted Police has few reserves able to provide a "surge" capability, and its French-speaking capability is more limited.

Significant use of the Canadian Forces in aid of the Quebec civil power includes two relatively recent major civil crises:
 * the October crisis of 1970
 * the Oka crisis of 1990

The federal government can and does use the military in aid of its own responsibilities, such as guarding federal buildings and facilities. Since 1993, the Canadian Forces have also provided the country's federal counter-terrorist forces, replacing the Royal Canadian Mounted Police in that function. (See JTF2 for details of request and control of this capability).

Germany
The post-war constitution of Germany strictly forbids the use of military force in police functions. The functions that MACP has in other countries are carried out by special police forces, which are basically under the control of the state governments, not of the federal government.

For some actions, federal police forces can be used either by orders of the federal administration and federal judiciary or by request of the state government. The counter-terrorist unit GSG 9 is part of the Bundespolizei (until 2005 known as the Bundesgrenzschutz) and is well known in Germany for its antiterrorist missions. However, several state police corps have similar units. The Bundesgrenzschutz and the GSG 9 were historically combatants and they had military ranks, but have always been under the control of the Ministry of the Interior.

This strict separation between civil and military power was enacted to prevent the army from becoming a political power again in internal affairs and to secure its subordination to the civil power. Since the 1990s, a number of conservative politicians has called for an abolition of this rule, but there seems to be no majority for such a change.

But a new law was passed in September 2004, the Air Security Act (Luftsicherheitsgesetz). From September 24, 2004 until February 2005 there was an exception from the use of military force regarding air security: In a case of imminent danger, the Bundeswehr and its air force branch, the German Air Force were authorised to use force against an aircraft.

As ultima ratio, the Minister of Defense was empowered to give the order to shoot down an aircraft if the aircraft was used as a weapon against humans and there was no other way to repel the attack. Air policing is a traditional task of the German Air Force. However, the Luftsicherheitsgesetz was declared unconstitutional on February 15, 2006, by the Federal Constitutional Court of Germany Bundesverfassungsgericht).

The court held that no civil aircraft may be shot down, even if the aircraft is used as a weapon by terrorist. The court held that the passengers' dignity and right to life would be violated if the aircraft was shot down.

Ireland
In Ireland, the Defence Forces provide assistance through Aid to the Civil Power (ATCP) arrangements to the Government of Ireland. The Army, Naval Service and Air Corps also provide Aid to Civil Community and Aid to Government departments, particularly in a supplementary role to the Garda Síochána, the national police force. Responsibilities include national security, prisoner, cash, ammunition and explosives transport, maritime safety, search and rescue, drug interdiction, fisheries protection, patrols of vital state installations and border patrols (including armed checkpoints), air ambulance service and non-combatant evacuation. Examples include; Garda Air Support Unit (GASU) aircraft being flown and maintained by Air Corps personnel, the Air Corps and Naval Service assisting in search and rescue (the Irish Coast Guard (IRCG) is a civilian agency which operates in the Republic of Ireland and some parts of Northern Ireland), the Army Ranger Wing (ARW) carrying out domestic counter-terrorism operations and the Directorate of Intelligence (G2) carrying out domestic counter-intelligence duties.

Italy
In 2008 the Italian Government decided to use soldiers from the Army, Navy and Air Force to patrol the cities and protect risky buildings (embassies, consulates, monuments). When they patrol the cities they are always accompanied with an agent from the Polizia di Stato (State Police), a military from the Carabinieri or a military from Guardia di Finanza.

It must be reminded that Carabinieri are the 4th Armed force in Italy while Guardia di Finanza are a military body.

United Kingdom
In the United Kingdom, Military Aid to the Civil Power is one of the three classifications of Military Aid to the Civil Authorities. MACP encompasses the provision of military assistance (armed if necessary) in its maintenance of law, order and public safety using specialist capabilities or equipment in situations beyond the capability of the Civil Power. This includes capabilities such as Explosive Ordnance Disposal, air-sea rescue (where it is provided by the RAF Search and Rescue Force) and mountain rescue (where it is provided by the Royal Air Force Mountain Rescue Service)

United States
The Posse Comitatus Act, passed in 1878, generally prohibits Federal military personnel (except the United States Coast Guard) and units of the United States National Guard under Federal authority from acting in a law enforcement capacity within the United States, except where expressly authorized by the Constitution or Congress.

The original act only referred to the Army, but the Air Force was added in 1956 and the Navy and Marine Corps have been included by a regulation of the Department of Defense. This law is mentioned whenever it appears that the Department of Defense is interfering in domestic disturbances.

However, the National Guard may still be used for police-like duties if still under control of the state, as with the 1967 Detroit riot.

Repeated caveats have been added to the Posse Comitatus Act over the years by subsequent legislation.