It is core to the post-Brexit security cooperation debate that the question of why the EU blocked the UK from accessing its migration databases has become a key issue. The EU blocked the UK from migration databases, including the Schengen Information System (SIS II) and Eurodac, in May 2025 as part of its “Brexit reset” negotiations. This decision has drawn criticism in London, particularly from Prime Minister Keir Starmer, who views database access as crucial to combating illegal migration and enhancing cross-border intelligence sharing. This article explores the legal, political, and strategic factors behind the EU’s refusal, and assesses the implications for UK-EU cooperation on migration and border security.
UK Blocked from Key EU Migration Databases
Since leaving the EU in January 2021, the UK has sought to restore aspects of its pre-Brexit security relationship, including access to EU databases. The problem of why the EU blocked the UK from migration databases was first raised in the open when British officials were informed that Brussels would not grant access to SIS II or Eurodac. Contextually, SIS II is key to real-time warnings on criminals and missing people, and Eurodac holds fingerprints of illegal immigrants—a “gamechanger” for determining asylum applications, UK officials. Lacking these figures, the UK’s border security apparatus remains hamstrung.
A Key Sub-Issue: Why the EU blocked the UK from migration databases
One underlying question is: why did the EU block the UK from accessing migration databases, even when both parties had repeatedly made promises of mutual benefit? Brussels officials have cited legal constraints and fear of establishing a precedent. Granting access to SIS II or Eurodac to a non-Schengen, non-EU country would require treaty amendments, compromising the system’s exclusivity and possibly creating a flood of other third-party requests. EU sources describe the UK stance as “intransigent” and “dogmatic”.
The Strategic Importance of These Databases
Before Brexit, the UK had partial access to SIS (no visa-free travel, but cooperation in asylum and crime). Eurodac helped determine if asylum seekers had previously made claims in an EU member state. UK Home Office officials say that access to Eurodac would have allowed them to “swiftly determine where an asylum seeker had claimed previously” and speed up removals, especially with the country’s stretched hotel accommodation system, which is costing taxpayers up to £5.5 million per day.
The UK government’s 2025 proposal entailed:
• Demanding to know why the EU blocked the UK from migration databases to reveal the underlying legal issue.
• Proposing alternatives: read-only access, technical bridging, or observer status.
• Pointing out other third countries (notably Ireland) that had preserved some SIS access since 2021 but through unique bilateral agreements and claiming that the UK was a “major security partner” whose exclusion was self-contradictory.
Political and Legal Reasons
Legally, the EU retains the right to exclude third countries from accessing SIS II and Eurodac, subject to strict conditions based on treaty obligations and EU legislation. Politically, there is a fear of slippage: granting the UK privileged access would send the wrong signal to other non-EU states, encouraging them to request similar treatment. EU negotiators have repeatedly stated: “No matter how transparent the mutual gain, they’re not moving”—using terms such as “intransigent” and “dogmatic” to describe the UK stance.
Impact on Security and Border Control
Without these databases, UK authorities do not get real-time warnings on criminal suspects or fingerprint data. This weakens attempts to stop small boat crossings, people smuggling, and cross-channel criminal migration. Labour Home Secretary Yvette Cooper stated that the current situation is causing “gaps in real-time intelligence sharing” with serious consequences for national security.
London has tried to compensate by proposing:
• New security deals focus on collaborative operations and intelligence sharing outside EU systems.
• New border security infrastructure investment.
• Faster return through third-country deals.
These are temporary measures, not replacements for complete SIS II and Eurodac functionality.
Brexit Reset Broader Negotiations
The database problem is part of a multi-pillar “EU reset” policy. Other agenda items include youth mobility plans, trade and veterinary standards, and fishing. Additionally, they cover membership in Horizon programs and mutual recognition of professional qualifications. However, UK sources have warned EU negotiators that they can’t proceed with youth visas or other provisions until they understand why the EU blocked the UK from migration databases. EU negotiators, not wanting to appear weak, have instead suggested “considering possible future cooperation” without committing themselves to formal legal agreements while emphasising the need for treaty amendment.
Domestic Political Fallout
In the UK, the refusal elicited widespread outrage. Opposition MPs accused the government of its negotiating stance as “short on strategic clarity.” Citizen groups involved in migration and refugee issues warned that the Home Office would continue to face delays and court cases in processing asylum applications in the absence of access. In Brussels, EU leaders explained the decision as a defence of the integrity of mutual systems. Germany and France are long-standing allies in EU-UK migration talks and demanded broader migration cooperation. However, they stopped short of calling for database access without treaty revision.
EU’s Legal and Practical Precedence
The cause of the EU’s caution lies in one of the legal precedents. Allowing third-party access to SIS II would require Brussels to reopen the relevant treaties. This is an unpopular move that demands unanimous approval from all EU member states. EU diplomats insist that the issue is not rooted in distrust of the UK itself but in upholding legal principles and consistency. EU analyst Jonathan Barrett explained that making snapshot access available would undermine database exclusivity and risk misuse via fragmentation: “Granting one non-member access could unravel years of agreed-upon judicial and security norms.”
UK Alternatives Under Consideration
The UK is exploring two main alternatives to restore some access:
1. Technical Workarounds: Developing UK-controlled systems that mimic SIS/EURODAC capability via bilateral intelligence-sharing agreements.
2. There are suggestions to deploy a voting liaison or analyst into EU institutions. This follows the precedent set by previous collaborations with Europol.
Both have yet to be accepted by the EU. The EU views them as inadequate replacements despite acknowledging the need for coordinated security measures.
Legal Barriers, Security Costs: The UK-EU Data Access Dilemma
The EU blocks the UK from accessing migration databases, encapsulating a broader tension between legal principles and security pragmatism. Brussels sees the refusal as necessary to avoid diluting treaties. Meanwhile, London believes that shared security interests should take precedence over treaty rigidity. The impasse will not be disentangled easily unless the law is seriously renegotiated—a route the EU is reluctant to pursue. Meanwhile, both parties must get creative with their cooperation through bilateral data sharing, new treaties, and coordinated action. However, without SIS II and Eurodac, the UK remains at a disadvantage in combating illegal migration and cross-border crime. Breaking the stalemate requires trust—but above all, a powerful political will that is strong enough to uproot entrenched legal frameworks. The explanation for why the EU blocked the UK from migration databases lies in treaty restrictions and established legal precedents. However, security risks do not have the courtesy to respect legal subtlety.
