The prospect of a no-deal Brexit has led to some dystopian predictions about what might happen if the UK leaves the EU without a transition plan in place on March 29. Councils in Kent warned of impending gridlock on the roads and supermarkets of a disruption to food supplies of and possible price rises. Several newspapers with differing stances on Brexit reported on the potential for military deployment to help maintain public order.

Whether this is rooted in genuine concern or political alarmism, it’s true that the military can legally be called in to help in certain circumstances. And at times of crisis, it’s common for some to call for military deployment. It happened during the English riots in 2011, and has been a regular feature during prison riots ever since the 25-day riots at Strangeways prison in 1990. In the worst prison riots in Scotland in 1987, special forces unit the SAS were eventually sent in.

Contingency plans where the military will step into the role of law enforcement – either in the guise of police or prison officers – happens more regularly than some people seem to think. It’s often part of standard preparations for a worst-case scenario.

Read more: No-deal Brexit: preparing for nuclear fallout influenced how government plans for worst-case scenarios

First, call for more police

In an ideal world, contingency plans provide the police with a set of clear instructions that provide a multi-agency response to events such as man-made disasters, infrastructure failure, terrorism and riots. But since 2010, successive Conservative governments have pursued a policy of austerity within the public sector which removed more than 30% from policing budgets, leading to drastic reductions in the number of police officers across England and Wales. This will limit what plans police forces can put in place to manage any public disorder.

The main way to manage shortages in policing is via the use of what is termed “mutual aid”, where one force can request public order support from another force anywhere across England and Wales. Such mutual aid can be requested either in advance, which is often done for the policing of large-scale public events such as football matches, or at short notice during an emergency. The officers are then seconded to the force that has requested their presence and can exercise all of the powers of a constable of that force without jurisdictional issues arising.

Such borrowing of officers is based on the assumption that public order incidents are localised and only need a minor increase in manpower to be contained. It’s conceivable that should no-deal Brexit lead to large-scale disruption to food supplies and essential services then public order incidents could happen in numerous locations. With police office numbers already stretched to breaking point, the required manpower would inevitably have to come from elsewhere. This is where the military could step in.

Legal grey area

The government policy that regulates military help is called Military Aid to the Civil Authorities (MACA), governed in law by the Civil Contingencies Act 2004. MACA is broken down into three broad areas, each of which has its own specific governing principles and legislation. The one that would have most relevance in the case of Brexit is “military aid to the civil power”, which provides armed, emergency support to the state to help maintain law, order and public safety.

The law gives the government the legal right to ask the military to provide aid to civil authorities should the need arise. This aid can take the form of niche capabilities – such as when army Green Goddess fire engines were called in during strikes by firefighters in 2002 – or manpower, which can be armed or unarmed. The military were quickly co-opted, under this law, for their specialist capacities when Gatwick Airport was closed in late December 2018 by reports of drone sightings.

Philip Toscano/PA Archive

Troops were also deployed under this act in the aftermath of the Manchester Arena attack in 2017 to guard several high profile sites across the country. In that case, the deployment of uniformed, armed soldiers seemed, on the surface, to be a proportionate response to the threat of further terrorist incidents. But this sort of deployment is not the niche capability that the MACA framework is designed for and could leave soldiers in a legal grey zone.

Unlike the police, soldiers are trained to fight in conflict situations where lethal force is necessary. In contrast, the police routinely also use force, but to maintain order and protect life and property.

If the army was used to maintain public order, it could lead to them controlling crowds and potentially making arrests. The MACA policy framework allows for the military to be used in a civil response role – but is less clear about its use in a role that requires less than lethal force. That sort of policing of public disorder is properly and rightfully the responsibility of the police.

The last time the British army attempted such a public order role was during the Troubles in Northern Ireland. Incidents such as Bloody Sunday – where 14 people died after British paratroopers fired on a march in Derry – stand as proof that the militarisation of public order policing is fraught with risks. Policing starkly divided emotions, frustrations and opinions on Brexit is a difficult task, but one principally for the police.