What is immigration detention?

Indefinite immigration detention is inhumane and a fundamental abuse of  human rights.

Detention Action exists to defend the rights of people held in immigration detention centres by the UK Government and end indefinite detention and other unjust detention policies.

Immigration detention is the practice by the government of locking people in detention centres while their immigration status is resolved. It is a form of administrative detention, not criminal justice or punishment.

However, conditions in immigration detention mirror those of a prison. In most cases, people are held in small cells with barred windows, where they are locked in for several hours during the day and at night. Healthcare services are often under-resourced and access to legal support and contact with friends and family is extremely limited.

Around 24,000 people were detained last year in seven detention centres – also called Immigration Removal Centres (IRCs) – located across the country. These facilities are run for profit by private companies. 

The Home Office decides who should be detained. As of 2023, the Home Secretary also has the power to remove people, including unaccompanied children, to “safe” foreign countries with which the UK has a removals agreement. However, currently no such removal agreements have been established.

The United Kingdom is the only country in Europe with no time limit on immigration detention, meaning that people held in detention by the government do not know when they will be released and, in some cases, are detained for years at a time.

Detention should be used only as a last resort and for the shortest time possible. It should not be used as a punishment and is not for the purpose of public protection (which is the job of prisons and the criminal justice system). In recent years, the Home Office has been holding more people in prisons under immigration detention powers after those people have completed a prison sentence.

In reality, immigration detention is used far beyond its stated purpose. The Government holds people in immigration detention centres for periods ranging from days to several years. This includes people who have lived in the UK since childhood, people fleeing war and persecution and people who have survived torture and trafficking. The Illegal Migration Act, passed in July 2023, will significantly increase the number of people detained, while at the same time removing critical safeguards to protect them from abuse and unlawful detention. It gives the Home Secretary a series of new powers, including the power to detain children indefinitely. 

In 2022, 95% of people in detention were ultimately released. 78% of all individuals held in detention during that year were released on bail, and 73% were released after fewer than 28 days. High release rates indicate that, in many cases, detention – and the harm it causes – is unnecessary. 

People can be detained at different points in their immigration journey. Some people are detained on arrival to the UK or when they claim asylum, often in Short-Term Holding Facilities like the Manston facility in Kent. Some people are detained after completing a criminal sentence. Others may be detained after living in the UK for years or even decades. Detention Action regularly supports people who are detained and threatened with deportation, despite having British children who would be deprived of a parent if they were removed.

Many people in detention cannot return to their countries of origin, even if they want to.

Some are stateless, which means they do not have citizenship of another country. Under international law, stateless people have similar rights to refugees and should be allowed to stay, but many find themselves detained indefinitely. Others cannot return to their country of origin because they lack the necessary paperwork or their country will not accept them back for other reasons. Other people in detention have lived in the UK legally for many years or decades, and can no longer prove their original nationality. 

Some people cannot be returned because their country of origin is too dangerous. For example, many people from Afghanistan and Syria cannot be deported because of the dangers involved in travelling there. Some of those people are then detained indefinitely, instead of being allowed to live in the community. 


Indefinite detention also has a high human and financial cost. The physical and mental health problems caused by detention are well documented. The British Medical Association (BMA) has stated: 

Various studies have identified the negative impact of immigration detention on mental health, and that the severity of this impact increases the longer detention continues. Depression, anxiety, and post-traumatic stress disorder (PTSD) are the most common mental health problems, and women, asylum seekers, and victims of torture are particularly vulnerable. 

According to Oxford’s Migration Observatory, the cost of immigration detention in 2022 was at a record of £107 per person per day, The cost of running the detention estate in 2013/14 was £164.4m. Under the provisions of the Illegal Migration Act, the UK Government is projected to spend at least £3.8 billion within the first three years of the legislation coming into effect. This cost would be in addition to payouts associated with unlawful detention claims.

In the year ending March 2022, there were 572 proven cases of unlawful detention, as a result of which a total of £12.7 million was paid in compensation. This is an increase of £11.9 million from 2015.