The Illegal Migration Act 2023 (“IMA”) became law on 20 July 2023. However, the majority of its provisions are yet to be brought into force.

The Supreme Court is currently reviewing the government’s plan to send asylum seekers to Rwanda. If the Supreme Court rules against the government it will throw the IMA into disarray.

The introduction to the IMA itself proudly and unreservedly declares that the purpose of the Act is to “prevent and deter unlawful migration, and in particular migration by unsafe and illegal routes, by requiring the removal from the United Kingdom of certain persons who enter or arrive in the United Kingdom in breach of immigration control”.

The IMA is controversial for many reasons, not least because it places a duty on the Home Secretary to remove (for example to Rwanda) those who arrive in the UK without immigration permission, where they have passed through a safe third country. Whilst the removal of someone seeking asylum is being arranged, the plan is for the Home Secretary to be able to detain them.

Importantly, to facilitate the removal process, the IMA makes sweeping changes to the Home Secretary’s detention powers, impacting the ability to challenge detention, decision-making around reasonableness of detention and even removing limitations to the detention of children. Many of these changes are marked by the common feature of eroding judicial oversight.

This blog focuses on the changes to the Secretary of State for the Home Department's (SSHD) detention powers under the IMA, along with potential legal challenges that may arise.

Powers of detention before the IMA

Although not all of the IMA is currently in force, provisions amending the Home Secretary’s detention powers (including section 12 of the IMA) have already become law. The Home Secretary’s new detention powers are now much less restricted.

The IMA makes changes to the established four Hardial Singh principles, which limit the exercise of the Home Secretary’s detention powers. These are as follows:

  1. The Secretary of State must intend to deport the person and can only use the power to detain for that purpose;
  2. The deportee may only be detained for a period that is reasonable in all the circumstances;
  3. If, before the expiry of the reasonable period, it becomes apparent that the Secretary of State will not be able to effect deportation within a reasonable period, they should not seek to exercise the power of detention;
  4. The Secretary of State should act with reasonable diligence and expedition to effect removal.

Changes made by the IMA – now the Home Secretary gets to decide what is reasonable

Section 12 of the IMA entered into force on 28 September 2023 and has replaced, in part, the second and third principles. A pivotal aspect of the Hardial Singh principles is that it is the courts that decide whether detention is reasonable in order to give effect to removal. The IMA overturns this and places the power to determine what period of detention is reasonable firmly in the hands of the Home Secretary:

“A person liable to be detained under paragraph 16 may be detained for such period as, in the opinion of the Secretary of State, is reasonably necessary to enable the examination or removal to be carried out, the decision to be made, or the directions to be given”.

On the face of it, this appears to eliminate a fundamental safeguard protecting the right to liberty and freedom from arbitrary detention. However, we suspect this will face judicial challenge, since the standard of “reasonableness” under the Hardial Singh principles is reasonableness in the Wednesbury sense, meaning that a court can continue to find that a decision to maintain detention is objectively unreasonable, despite the SSHD’s contrary view.

The IMA also removes the option of judicial challenge

Although not yet in force, the IMA also (via section 13) introduces an “ouster clause,” meaning that it obstructs judicial challenge. It says that a person “must not” be granted immigration bail by the First-Tier Immigration Tribunal until 28 days after the detention has begun.

It also goes further by barring judicial review challenges to detention during the first 28 days of detention. The only exceptions are where the SSHD has acted in “bad faith” or “in such a procedurally defective way as amounts to a fundamental breach of the principles of natural justice”. Where the exceptions do not apply, a detention decision can only be challenged in the first 28 days by way of the ancient “writ of Habeas Corpus” (demanding that a court determines whether someone is unlawfully detained).

Criticism and scepticism

While being criticised as threatening the rule of law and the doctrine of the separation of powers, attempts to limit judicial oversight in this way are often met with scepticism by the courts and may be found unlawful under challenge. You can learn more about how courts respond to ouster clauses in a blog by Nick Wrightson, a partner in our public law team.

Given the purpose of the IMA set out above, the government plainly sees judicial action against detention of “illegal migrants” as a hindrance to its aims of facilitating swift removals.

What about the ECHR?

Another major safeguard against threats to human liberty are the rights protected under the European Convention on Human Rights (“ECHR”). The Human Rights Act 1998 gives domestic effect to the ECHR.

The government published a memorandum on 7 March 2023 explaining the compatibility of the provisions of the IMA with the ECHR. The Illegal Migration Bill itself was published with a statement by the Home Secretary that she was unable to confirm its compatibility with the ECHR. The government acknowledged in February 2023 that the Bill (as it then was) was “pushing the boundaries of what is legally possible, while staying within the ECHR’, adding that, if the legislation was ‘held up in Strasbourg’ the government is ‘willing to reconsider whether being part of the ECHR is in the UK’s long-term interests’.

Where does this leave us for the future?

The ongoing discourse on the UK's human rights regime, including legislation like the IMA and potential withdrawals from international human rights treaties, will likely persist, with direct and resoundingly negative consequences for refugees seeking asylum in the UK. With the government’s recent ramping up of anti-Strasbourg and flagrantly anti-immigrant rhetoric, it’s not a stretch to imagine further erosion of judicial oversight at the international level.

All eyes will be on the Supreme Court’s decision (due at the end of this year or the start of next) on the Rwanda plan. If the decision goes against the government’s plan, nothing can be ruled out in terms of the government’s willingness to amend the Rwanda plan, withdraw from the ECHR or take any other measure in order to proceed with full implementation of the IMA.