Section 24A
Citizen's Arrest
When Members of the Public Can Lawfully Detain a Suspect Under PACE 1984 (2026)
Statutory Definition
What Is Section 24A
Citizen's Arrest?
Section 24A of the Police and Criminal Evidence Act 1984 allows a person who is not a police officer to arrest someone who is committing an indictable offence, or who they reasonably suspect has committed such an offence.
The power is designed for situations where waiting for the police would allow the suspect to escape or cause harm.
However the arrest must be necessary and reasonable in the circumstances.
⚠ If the conditions of Section 24A are not met, the person attempting the arrest could themselves be committing offences such as assault, battery, or false imprisonment.
Chapter 1
Why Citizen Arrest Powers Exist
Citizen arrest powers existed long before modern policing. Historically, communities were collectively responsible for maintaining order before professional police services were established in the nineteenth century.
The ancient concept of "hue and cry" required members of the public to assist in pursuing and detaining criminals. This was not a right but a legal obligation enforceable at common law. If a victim raised the alarm, all those within earshot were required to join the pursuit.
When modern policing developed following the Metropolitan Police Act 1829, the law preserved limited public arrest powers as a residual emergency provision. Section 24A of PACE formalised these powers within a modern statutory framework.
Historical Foundation
Before PACE 1984, citizen arrest powers derived from common law. They were inconsistently defined and often misunderstood. PACE created a single statutory framework that clarified both when the power exists and what conditions must be satisfied.
The Modern Position
The expectation in modern policing is clear. If the police can deal with the situation, they should. Citizen arrest is intended only for situations where immediate intervention is genuinely required and a constable cannot realistically attend in time.
The law deliberately restricts citizen arrest powers to prevent misuse, vigilantism, and unnecessary confrontation. A member of the public exercising this power assumes significant legal and personal risk.
Unlike police officers, members of the public have no training in use of force, no legal powers of search, and no authority to detain beyond the narrow circumstances prescribed by Section 24A. The power is a safety valve, not a general licence to act as a police officer.
Chapter 2
The Legal Basis of Section 24A
Section 24A was inserted into PACE by the Serious Organised Crime and Police Act 2005 (SOCPA). Prior to this amendment, citizen arrest powers derived from the older concept of "arrestable offences" under earlier legislation. SOCPA reformed the entire arrest framework, simultaneously expanding police powers and codifying the limits of public arrest powers.
Section 24A(1) — Arresting During Commission
A person other than a constable may arrest without a warrant anyone who is in the act of committing an indictable offence, or anyone whom they have reasonable grounds for suspecting to be committing an indictable offence.
Section 24A(2) — Arresting After Commission
Where an indictable offence has been committed, a person other than a constable may arrest someone they reasonably suspect of having committed it. However, the offence must actually have been committed — not merely suspected. This is a stricter condition than that applicable to constables.
Section 24A(3) — The Dual Condition
The power under Section 24A(1) and (2) is exercisable only if two conditions are satisfied: (a) the arrest is necessary under one of the statutory necessity grounds; and (b) it appears to the person making the arrest that it is not reasonably practicable for a constable to make the arrest instead.
This creates a three-stage legal test: Stage 1 — reasonable grounds for suspicion of an indictable offence. Stage 2 — necessity under a prescribed ground. Stage 3 — impracticability of police attendance. All three must be satisfied or the arrest is unlawful.
This is deliberately more demanding than the test applied to police officers under Section 24. A constable does not need to establish that it is impracticable for another officer to attend. A member of the public does.
Chapter 3
What Is an Indictable Offence?
Citizen arrest powers under Section 24A are limited to indictable offences. This is a fundamental constraint that immediately removes the majority of everyday criminal behaviour from the scope of the power.
An indictable offence is one that may be tried in the Crown Court before a judge and jury. The category includes two sub-types, both of which qualify for Section 24A:
Indictable-Only Offences
These can only be tried in the Crown Court. They include murder, manslaughter, rape, robbery, and causing grievous bodily harm with intent. There is no question these qualify.
Either-Way Offences
These may be tried in either the Magistrates' Court or Crown Court. Theft, burglary, assault occasioning actual bodily harm, and most drug offences fall into this category. These also qualify under Section 24A.
Shoplifting and retail theft are either-way offences under the Theft Act 1968 when the value of goods exceeds a threshold — and even below that threshold, theft remains an either-way offence. This is why retail environments represent by far the most common setting for citizen arrest in practice.
Summary-Only Offences — Not Covered
Purely summary offences cannot justify a citizen arrest under Section 24A. These include drunk and disorderly behaviour under Section 91 of the Criminal Justice Act 1967, minor public order offences under Section 4A of the Public Order Act 1986, and most traffic offences. If someone is committing one of these offences, the lawful course of action is to call the police, not to physically detain them.
The distinction matters enormously in practice. A person who detains someone for a summary-only offence under the purported authority of Section 24A has no legal basis for that detention. The detained person would be entirely within their rights to resist, and the detainer could face criminal and civil consequences.
Chapter 4
Reasonable Grounds for Suspicion
A citizen making an arrest must have reasonable grounds for suspecting that an indictable offence is being or has been committed. This is an objective legal test assessed from the perspective of a reasonable person in possession of the same information.
The suspicion must be founded on facts, observed behaviour, or specific intelligence — not on assumption, stereotyping, or generalised unease. This is the same foundational principle that governs police suspicion under Section 24, and the courts apply it consistently across both.
Examples That May Satisfy the Test
Directly witnessing someone conceal items and leave a shop without paying
Observing someone commit a physical assault on another person
Watching someone break into a vehicle or building
Following a suspect immediately after witnessing the commission of an offence
Receiving immediate, specific information from a credible source identifying the suspect
Examples That May NOT Satisfy the Test
A general feeling that someone looks suspicious
Suspicion based solely on a person's appearance, ethnicity, or clothing
Being told by a third party without specific corroborating detail
Assuming guilt because someone is running or behaving nervously
Courts assess the reasonableness of suspicion at the moment the arrest was made, not retrospectively in light of what was subsequently discovered. If the grounds were reasonable at the time of arrest but the suspect was later found to be innocent, the arrest may still have been lawful. But if no reasonable grounds existed at the point of detention, the arrest is unlawful regardless of outcome.
An important asymmetry exists between police and public in the aftermath. Under Section 24A(2), a citizen may only arrest after an offence if the offence has actually been committed. If it turns out no offence occurred, the citizen has no valid basis for arrest under subsection (2) even if their suspicion was genuinely held and objectively reasonable. Police officers under Section 24 face no such restriction.
Chapter 5
The Necessity Requirement
Even where reasonable grounds for suspicion clearly exist, a citizen arrest is only lawful if it is also necessary. Section 24A(3) specifies that the power is only exercisable if the arrest appears necessary for one or more of the following reasons:
Prevent Physical Injury
To prevent the suspect causing physical injury to themselves or to any other person.
Prevent Property Damage
To prevent the suspect causing loss of or damage to property.
Prevent Escape
Where the suspect is making off before a constable can assume responsibility for them.
Protect the Suspect
To prevent the suspect suffering physical injury, particularly if endangered by others.
This necessity test is deliberately stricter than the one applied to police officers under Code G of PACE. Officers have a broader range of necessity grounds available including investigative purposes, enabling accurate identification of the person, and protecting vulnerable persons. Members of the public have none of these.
The most practically relevant necessity ground for citizen arrest is that the suspect is making off before a constable can assume responsibility. This is the ground that typically applies in shoplifting scenarios where a security officer stops someone who has left the store and is attempting to leave the area entirely.
The necessity test is not satisfied simply because an offence has occurred. The question is whether action right now is required to prevent one of the specified consequences. If the suspect is standing still and waiting, if they are calm and compliant, or if officers are moments away — necessity is far harder to establish.
Additionally, Section 24A(3)(b) requires that it appeared to the person making the arrest that it was not reasonably practicable for a constable to make the arrest instead. This further narrows the window in which the power can legitimately be exercised.
Chapter 6
Why the Police Must Not Be Readily Available
Section 24A(3)(b) requires that it be not reasonably practicable for a constable to make the arrest instead. This is arguably the most frequently overlooked element of the citizen arrest framework.
The requirement does not demand that police be entirely absent from the area. It requires that a constable cannot practicably take over. If officers are nearby and will arrive within moments, a citizen arrest may not be lawful even if all other conditions are met.
If uniformed officers are visible at the scene, a citizen arrest will almost certainly be unjustified.
Courts will scrutinise heavily whether immediate intervention was truly necessary before police arrival.
Where attendance would take significant time and the suspect is clearly about to escape, the condition may be met.
This requirement exists to minimise risk. Public detentions of suspects are inherently dangerous situations. They escalate rapidly, can involve bystanders, and place untrained individuals in potentially violent confrontations. The law deliberately reserves these situations for trained officers wherever possible.
Chapter 7
Use of Force During a Citizen's Arrest
Where a citizen arrest is lawful, reasonable force may be used to effect it. The authority for this comes from Section 3 of the Criminal Law Act 1967, which provides that a person may use such force as is reasonable in the prevention of crime or in effecting the lawful arrest of offenders.
The key word is reasonable. This is assessed objectively with reference to all the circumstances known to the person at the time. A court will consider:
The seriousness of the offence and the threat posed
Whether the suspect was attempting to escape
Whether less forceful means were available and practical
The size and apparent capability of the suspect
Whether any weapon was involved or threatened
The immediacy of the risk to the public
Critical Risk: Excessive Force
If force used goes beyond what a court later determines to be reasonable, the person making the arrest faces criminal liability for assault, actual bodily harm, or in serious cases grievous bodily harm. A lawful purpose does not automatically justify the level of force used to achieve it. Each must be assessed independently.
Unlike police officers, members of the public have no specific training, mandatory procedures, or organisational oversight governing their use of force. There is no accountability framework, body camera footage, or professional standards review. The legal exposure falls entirely on the individual.
The practical advice is straightforward: use the minimum force necessary to prevent escape and immediately call the police. Verbal instruction and physical blocking are always preferable to grappling or striking.
Chapter 8
What Happens After a Citizen's Arrest
Once a suspect has been detained, the person who made the arrest must deliver them to a police officer as soon as reasonably practicable. This is a legal obligation, not a discretionary choice.
The citizen arrest does not transfer investigative authority. The member of the public has no power to search the detained person, no power to question them under caution, and no authority to conduct any investigation. All of this transfers immediately to the attending constable.
What You Can Do
- — Detain the person physically if necessary
- — Tell them they are being detained
- — Call the police immediately
- — Observe and note evidence
- — Prevent escape using reasonable force
What You Cannot Do
- — Search the detainee without consent
- — Question under formal caution
- — Hold the person indefinitely
- — Handcuff or bind without extreme justification
- — Conduct any formal investigation
If police do not attend within a reasonable time, continued detention becomes increasingly difficult to justify legally. A court would expect the detaining person to have made every effort to secure police attendance urgently.
Chapter 9
Security Guards and Retail Detention
Security guards, store detectives, and loss prevention officers are among the most frequent users of Section 24A powers in practice. Retail theft is an either-way offence under the Theft Act 1968, and the environment of a retail store creates scenarios where the necessity conditions are regularly satisfied.
However — and this is crucial — security guards have exactly the same powers as any other member of the public under Section 24A. A security industry licence does not confer additional arrest powers. An SIA badge does not create police-like authority. Guards are not special constables.
The Standard Retail Detention Scenario
A store detective observes a person conceal merchandise and leave the store without paying. The suspect is seen to be walking away from the premises rapidly. The store detective believes the suspect will escape before police arrive. They stop the individual and escort them to a holding room pending police attendance. This scenario, properly managed, typically satisfies all Section 24A conditions: indictable offence (theft), reasonable grounds (direct observation), necessity (preventing escape), and impracticability of immediate police arrest.
Where retailers go wrong is in maintaining detention for longer than necessary, conducting searches without consent, making unfounded allegations, or applying excessive physical restraint. Each of these creates exposure to civil claims for false imprisonment, battery, or defamation.
Retail losses due to false imprisonment claims have in some cases exceeded the value of the goods originally stolen. Proper training and strict adherence to the Section 24A framework is therefore a matter of commercial as well as legal importance for retailers.
Chapter 10
Misconceptions About Citizen's Arrest
Popular culture — films, television dramas, and social media — has created widespread misconceptions about how citizen arrest actually works. These myths are legally dangerous.
"Anyone can arrest someone for any crime"
Citizen arrest only applies to indictable and either-way offences. Summary-only offences are entirely excluded.
"You must say 'I am placing you under citizen's arrest'"
No specific wording is required by law. However the person detained must be made aware of the fact of detention and the reason for it, as soon as practicable.
"Physical restraint is always justified during an arrest"
Force must be reasonable and proportionate. Excessive force exposes the arresting person to criminal liability regardless of how genuine their intention was.
"A citizen arrest makes you a temporary police officer"
No. You acquire none of the investigative powers of a constable. You cannot search, caution, or question. You simply hold the person until an officer arrives.
"Citizen arrest is a powerful tool against crime"
It is a narrow last resort. The legal thresholds are deliberately high. In most situations calling police is the correct and safest response.
Chapter 11
Risks of an Unlawful Citizen's Arrest
If the conditions of Section 24A are not met, the attempted arrest is unlawful from the moment of detention. The consequences can be severe.
False Imprisonment
CivilAny unlawful detention — no matter how brief — constitutes the tort of false imprisonment. Damages can be awarded for the period of detention, distress caused, and consequential losses.
Assault and Battery
Criminal/CivilAny use of physical force during an unlawful arrest is itself unlawful. Even the touching necessary to stop someone could constitute battery.
Kidnap
CriminalProlonged or forceful detention in circumstances well outside Section 24A could in extreme cases meet the threshold for kidnap under common law.
Criminal Charges
CriminalIn serious cases, a person who makes an unlawful arrest with significant force could face charges of GBH, unlawful imprisonment, or affray.
Courts take a dim view of vigilante behaviour. Even where the arrested person was subsequently convicted of the very offence suspected, an unlawful arrest may still result in civil liability for the person who made it. The lawfulness of the arrest is assessed entirely on what the arresting person knew and did at the time — not on the ultimate outcome.
Chapter 12
Real-World Examples
Retail Theft — Security Guard Detains Suspect
Facts
A store detective observes a man conceal a jacket worth £180 in a bag and walk past the payment tills. He exits the store and begins walking rapidly away. The detective pursues, identifies herself, and physically stops him at the car park entrance. She escorts him to a security room and calls police, who arrive within eight minutes.
Legal Analysis
Indictable offence: theft (either-way). Observable grounds: direct witness. Necessity: suspect making off before police could assume responsibility. Impracticability: suspect was actively leaving. Likely Section 24A compliant.
Witnessed Street Violence
Facts
A bystander witnesses a man repeatedly punch someone who has fallen to the floor. The attacker attempts to flee. The bystander grabs the attacker and holds him against a wall until police arrive two minutes later.
Legal Analysis
Indictable offence: assault occasioning actual bodily harm (either-way). Reasonable grounds: directly witnessed. Necessity: preventing further injury and preventing escape. Likely lawful, though force used must be proportionate.
Suspicion Without Witnessed Offence
Facts
A man sees someone acting oddly near parked cars and decides they are about to steal one. No offence has occurred. He grabs the person by the collar and demands they stay while he calls police.
Legal Analysis
No offence witnessed. No reasonable grounds that an indictable offence had been committed. Section 24A(2) requires an offence to have actually been committed. No necessity ground is met. This is false imprisonment regardless of the suspect's intentions.
Excessive Response to Shoplifter
Facts
A security guard detains a suspected shoplifter and, when the person attempts to pull away, strikes them twice in the face causing a broken nose. The suspect was attempting to leave, not attacking the guard.
Legal Analysis
Even if the initial detention was lawful under Section 24A, the force used was disproportionate. The guard is likely liable for assault causing actual bodily harm. A lawful arrest does not authorise unlimited force.
Chapter 13
Case Law and Judicial Interpretation
Courts have consistently interpreted citizen arrest powers narrowly. The following themes emerge consistently from the case law:
Reasonableness Is Assessed at the Time of Arrest
Courts examine what the arresting person knew and believed at the moment of detention, not what was later discovered. Subsequent guilt of the suspect does not retrospectively validate an unlawful arrest, and subsequent innocence does not automatically invalidate a reasonably held suspicion.
The Necessity Condition Must Be Separately Established
Courts distinguish between the grounds for suspicion and the grounds for necessity. Both must independently be satisfied. Even strong suspicion of an indictable offence does not by itself make the arrest necessary. The arresting person must be able to articulate why one of the prescribed necessity conditions applied at that moment.
Civil Liability Is Strict
False imprisonment is a strict liability tort. A claimant does not need to demonstrate malice, bad faith, or any intent on the part of the detainer. Where detention was without legal basis, the mere fact of unlawful restraint is sufficient to ground a claim for damages.
The Asymmetry Between Police and Public Powers Is Deliberate
Where challenges have been brought arguing that the restriction on public arrest powers is unjustified, courts have consistently upheld the distinction. The additional conditions applied to citizen arrests reflect the absence of training, accountability, and oversight mechanisms that exist for police officers.
Chapter 14
Operational Reality
From a policing perspective, situations involving citizen arrests are treated with careful professional scrutiny on arrival. Officers must satisfy themselves that the initial detention was lawful before assuming responsibility for the suspect. Where there is doubt, officers may have to consider whether they have independent grounds for their own detention or arrest.
Well-intentioned interventions by members of the public can sometimes complicate rather than assist police responses. Suspects who have been restrained without legal basis may resist lawful police detention on the grounds that the initial detention was unlawful — a position that courts have occasionally accepted.
The Practical Advice Given by Legal Professionals
In almost all situations, calling police and acting as a reliable witness is the safest legal course of action.
Citizen arrest should only be considered where an offence is actively occurring or has just occurred and the suspect is clearly about to escape.
Any force used must be the minimum necessary. Step back the moment the suspect stops resisting.
Document everything as soon as possible — what you saw, why you acted, what was said, what force was used.
Inform the suspect clearly and calmly why they are being detained.
Call police immediately and make their attendance an urgent priority, not an afterthought.
Section 15
Authority FAQ
Structured for featured snippet extraction. Each answer is self-contained and legally precise.
What is Section 24A PACE?
Section 24A of the Police and Criminal Evidence Act 1984 allows a person who is not a police officer to arrest someone who is committing an indictable offence, or who they reasonably suspect has committed such an offence. The arrest must be necessary and it must not be reasonably practicable for a constable to make the arrest instead.
Can anyone make a citizen's arrest in the UK?
Yes, but only under strict legal conditions. The offence must be indictable. The arrest must be necessary to prevent the suspect escaping, causing injury, or causing property damage. And it must not be reasonably practicable for a police officer to make the arrest instead.
What offences allow a citizen's arrest?
Only indictable offences and either-way offences qualify. These include robbery, burglary, assault occasioning actual bodily harm, theft, serious criminal damage, and drug supply offences. Summary-only offences such as drunk and disorderly do not qualify.
Do you have to say 'citizen's arrest'?
No specific wording is legally required. However the person being detained should be made aware they are being detained and the reason for that detention, as soon as practicable. This mirrors the obligations under Section 28 PACE for police arrests.
Can security guards arrest people under Section 24A?
Yes. Security guards have no additional powers beyond those available to any member of the public under Section 24A. They must satisfy the same conditions: indictable offence, reasonable grounds for suspicion, necessity, and impracticability of police making the arrest.
What force can be used in a citizen's arrest?
Reasonable force may be used under Section 3 of the Criminal Law Act 1967. Force must be proportionate to the circumstances. Excessive force could expose the person making the arrest to criminal liability for assault, battery, or grievous bodily harm.
What happens if a citizen's arrest turns out to be unlawful?
If the conditions of Section 24A are not met, the person making the arrest could face civil claims for false imprisonment or battery, and potentially criminal charges including assault. Even if the suspect was guilty, an unlawful arrest may still result in civil liability.
Is citizen's arrest common in the UK?
In practice it is relatively uncommon. The most frequent examples occur in retail theft situations where a store detective or security officer detains a suspected shoplifter until police arrive. Violent intervention by members of the public is rare and carries significant legal risk.
Section 16
Statutory Framework
PACE 1984, Section 24A
The primary statutory basis for citizen arrest powers. Inserted by SOCPA 2005, it consolidates and limits the conditions under which a member of the public may arrest without a warrant.
Criminal Law Act 1967, Section 3
Authorises the use of reasonable force in the prevention of crime and in effecting the lawful arrest of offenders. Applies to citizens and police officers alike.
PACE 1984, Section 28
Requires that any person under arrest be informed of the fact and grounds of their arrest as soon as reasonably practicable. Courts interpret this as applying to citizen arrests by analogy.
Conclusion
A Narrow Power.
A High Threshold.
Citizen arrest powers remain a legally important but operationally rare part of UK criminal law. Section 24A provides a narrow, tightly conditioned authority for members of the public to intervene when serious offences occur and police cannot practically attend in time.
The three-stage legal test — indictable offence, necessity, impracticability of police attendance — is deliberately demanding. This is not an accident. The law recognises that untrained individuals exercising physical authority over others creates significant risks of harm, misidentification, and injustice.
Misuse of the power carries serious legal consequences including civil liability for false imprisonment and criminal exposure for assault. The fact that a person acted in good faith, or that the suspect later proved to be guilty, does not automatically insulate them from liability.
In most circumstances — even those involving apparent criminal behaviour — the correct and legally safest course of action is to call the police, observe carefully, note details, and act as a reliable witness rather than an active detainer.
Citizen arrest is a last resort reserved for situations where immediate action is the only reasonable option. Understanding its limits is as important as knowing the power exists.
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