Law Enforcement
What is the difference between arrest and detention, and what limits both?
Arrest is an act; detention is the state that follows it. This guide explains the distinction, the safeguards attached to each, and why the specific thresholds are set by national law rather than by any universal rule.
In short
Arrest is an act: the moment a person is deprived of their liberty by an official exercising a legal power. Detention is the continuing state that follows — being held, somewhere, by someone, under some authority.
The distinction matters because different safeguards attach to each. The safeguards on arrest ask whether the deprivation was justified at the moment it began; the safeguards on detention ask repeatedly whether it remains justified, and for how much longer.
Why it exists
Depriving someone of liberty is, after the use of force, the most serious ordinary power an enforcement body holds. It is also the power most easily used for purposes other than the one it was granted for — to punish without trial, to obtain a statement, or to remove someone from circulation.
AnalysisThat is why the safeguards are structured around time and review rather than around the initial decision alone. An arrest is a single judgement made quickly, often on incomplete information; the framework accepts that and compensates by requiring the judgement to be re-examined by someone else, soon, and in a form that leaves a record.
The Universal Declaration of Human Rights states the declared principle that no one shall be subjected to arbitrary arrest, detention or exile, alongside the right to an effective remedy.
How it works
Across systems that differ in almost every detail, the safeguards tend to appear in the same five places.
- A legal basis, stated in advance
- The power must come from law, and the grounds must be ones the law recognises. "There was a good reason" is not a legal basis; it is a description of one.
- A threshold of suspicion
- Some level of objective justification is required before liberty may be removed. The level, and the words used to describe it, are set nationally — which is why the terminology in this area travels so badly.
- Being told why
- A person deprived of liberty is generally entitled to be told the reason. Without it, none of the other safeguards can be exercised, because the person cannot challenge a reason they have not been given.
- A time limit and external review
- Police detention is bounded, and continuing it beyond a point normally requires authorisation from outside the investigating team — a senior officer, a prosecutor, or a court. This is the safeguard that most reliably distinguishes systems.
- A record
- Times, decisions, and the identity of the decision-maker are recorded. The record is what makes every preceding safeguard checkable rather than asserted.
The International Covenant on Civil and Political Rights is the treaty in which many of these guarantees are expressed for states that have ratified it; it binds only those states, and says nothing about how any individual state applies it.
How much of this is left to statute rather than practice is itself a design choice. In England and Wales, for example, stop and search, entry and search, arrest, detention, and the questioning and treatment of detained persons are each dealt with in separate Parts of a single named Act, the Police and Criminal Evidence Act 1984, with codes of practice made under it.
Common misconceptions
Widely held beliefs that do not match how the system actually operates.
Common belief: Arrest and detention are two words for the same thing.
In practice: They are an act and a state. A person can be arrested and released within minutes, or detained for a period during which the justification has to be revisited more than once. Most of the safeguards that matter attach to the second, not the first.
Common belief: Being arrested means being charged.
In practice: In most systems arrest is an investigative step, not an accusation that has been tested. Whether a charge follows is usually a separate decision, frequently taken by a different person — in many countries a prosecutor rather than the arresting body.
Common belief: The thresholds are the same everywhere, just translated differently.
In practice: They are not. Standards of suspicion, maximum periods in police custody, and the point at which a court must become involved differ substantially between countries — including between countries that have ratified the same treaties.
Common belief: If a detention was lawful when it began, it stays lawful.
In practice: Lawfulness is a continuing requirement. Detention that was justified on arrest can become unlawful because its purpose has been achieved, because a time limit has expired, or because the authorisation that extended it was never obtained.
How this varies between jurisdictions
A required section on every guide. Arrangements differ between countries, and we say how.
- Whether a prosecutor, an investigating judge, or the police themselves direct the investigation changes who authorises continued detention and when.
- Maximum periods in police custody before a person must be brought before a judicial authority differ by country, and often by offence within a country.
- Some systems draw a sharp line between administrative detention and criminal detention, with different rules and different oversight bodies; others do not use the distinction at all.
- What must be recorded, and whether interviews are audio or video recorded, is a matter of national law and practice rather than international requirement.
- Whether a lawyer may be present during questioning, and from what moment, is one of the deepest structural differences between systems.
For how these choices are actually made in a given system, the country dossiers are the appropriate place — for example law enforcement in Germany or in France.
Rights and accountability
Detention is the setting in which record-keeping does the most work, because the person affected is least able to evidence what happened to them and the institution holds all of the documentation.
United Nations guidance on police accountability treats this as a matter of institutional design rather than individual conduct: because statutory provisions are often insufficient for the day-to-day exercise of powers, services are expected to issue professional standards giving practical guidance — and its own worked example of where such guidance is needed is arrest and detention procedure.
- Custody records establish times, decisions and decision-makers, and are frequently the only contemporaneous account.
- Independent inspection of places of detention exists in many systems as a standing function rather than a response to complaints.
- Evidence obtained through a breach of detention safeguards may be excluded, which links the safeguard directly to the outcome of the case.
What we could not establish
- The thresholds that actually decide whether an arrest is lawful — what suspicion is required, how long a person may be held before seeing a court, what must be recorded — are set by domestic law and differ substantially between countries. This guide states the shape of the safeguards, not the test in any jurisdiction.
- Terms in this area translate badly. "Arrest", "detention", "custody" and "remand" do not map cleanly between legal systems, and a word that names a specific procedure in one country may be a general description in another.
Where to go next
Related: police use of force, what is due process, and what is a criminal investigation. For the constitutional periods this page deliberately does not state, see how soon a detained person sees a judge.
Related topics
- When may police use force, and what limits apply?
Force is the most consequential thing an enforcement body does. This guide explains the international principles that govern it — necessity, proportionality and precaution — and why the limits are part of the power rather than an exception to it.
- Which bodies can examine what the police did, and what can each of them actually do?
Internal investigation, independent complaints bodies, inspectorates, prosecutors and courts examine police conduct in different ways and with different powers. This guide explains what each mechanism is for and why the differences between them matter to anyone trying to use one.
- What is due process?
Due process is the requirement that the state follow fair, established procedures before it takes action against a person. This guide explains what it typically includes and how it differs between systems.
- Can a person be held under emergency powers without being suspected of an offence?
Where a constitution provides for it, it usually provides conditions in the same breath. South Africa attaches eight of them to detention without trial; Brazil requires an arrest under emergency powers to be communicated to a judge immediately; one system bars discriminatory internment outright.
Sources
Universal Declaration of Human Rights
United Nations · International organisation · 1948-12-10 · link verified 2026-07-23
Supports the existence and wording of the declared principles of equality before the law (Art. 7), the right to an effective remedy (Art. 8), the right to a fair and public hearing by an independent and impartial tribunal (Art. 10), and the presumption of innocence (Art. 11). A declaration, not a treaty: it does not establish binding obligations, and it does not support any claim about how a particular state implements these principles.
United Nations · International organisation · 1966 · link verified 2026-07-23
Authentic treaty text as registered in the UN Treaty Series; registered ex officio 23 March 1976. Supports the fair-trial guarantees of Article 14, including the right to a competent, independent and impartial tribunal established by law, and the presumption of innocence (Art. 14(2)). Binding only on states party to it; does not support claims about states that have not ratified, nor about how any individual state applies it. WAVE 19 ADDITION, read from the same authentic treaty text in the UN Treaty Series PDF, text-extracted locally. Supports Article 14(5) in full: "Everyone convicted of a crime shall have the right to his conviction and sentence being reviewed by a higher tribunal according to law." The qualifier "according to law" is part of the provision and is load-bearing: the right is to review as the law of the state provides, not to appeal without limit or by any chosen route. Supports Article 14(6): where a person has by a FINAL decision been convicted of a criminal offence and the conviction has subsequently been reversed or the person pardoned on the ground that a new or newly discovered fact shows conclusively that there has been a miscarriage of justice, the person who has suffered punishment as a result shall be compensated according to law, unless it is proved that the non-disclosure of the unknown fact in time is wholly or partly attributable to that person. Supports Article 14(3)(g), that no one shall be compelled to testify against himself or to confess guilt, and Article 14(4), that the procedure for juvenile persons shall take account of their age and the desirability of promoting their rehabilitation. WAVE 20 ADDITION. PROVENANCE, stated precisely because this record's url is a different copy: the Article 4 material below was read on 2026-08-26 from OHCHR's official PDF of the Covenant at https://www.ohchr.org/sites/default/files/ccpr.pdf. The United Nations Treaty Series copy at this record's url timed out repeatedly this session and was not re-read, so nothing in this addition rests on it. Article 4 is the derogation clause, and its four cumulative conditions are the point. Supports ICCPR Art. 4(1): “1. In time of public emergency which threatens the life of the nation and the existence of which is officially proclaimed, the States Parties to the present Covenant may take measures derogating from their obligations under the present Covenant to the extent strictly required by the exigencies of the situation, provided that such measures are not inconsistent with their other obligations under international law and do not involve discrimination solely on the ground of race, colour, sex, language, religion or social origin.”. Supports ICCPR Art. 4(2), read with Arts. 6, 7, 8, 11, 15, 16 and 18 as printed in the same document: “2. No derogation from articles 6, 7, 8 (paragraphs 1 and 2), 11, 15, 16 and 18 may be made under this provision.”. Supports ICCPR Art. 4(3): “3. Any State Party to the present Covenant availing itself of the right of derogation shall immediately inform the other States Parties to the present Covenant, through the intermediary of the Secretary-General of the United Nations, of the provisions from which it has derogated and of the reasons by which it was actuated. A further communication shall be made, through the same intermediary, on the date on which it terminates such derogation.”. The Covenant binds States Parties to it. It is NOT evidence of any particular state's domestic law, and no country claim on this platform rests on it. It designates no organ to proclaim an emergency, assigns no role to any national legislature, and creates no civil-protection institution. The Human Rights Committee's interpretation of this article is cited separately and attributed to the Committee.WAVE 21 ADDITION. Read from the same United Nations Treaty Series PDF, text-extracted and searched. Supports Art. 9(1)-(4), and specifically that the Covenant polices ARBITRARINESS rather than closing a list of grounds: “Everyone has the right to liberty and security of person. No one shall be subjected to arbitrary arrest or detention. No one shall be deprived of his liberty except on such grounds and in accordance with such procedure as are established by law”; with 9(2) (informed at the time of arrest of the reasons and promptly of any charges), 9(3) (brought promptly before a judge or other officer authorised by law to exercise judicial power; it shall not be the general rule that persons awaiting trial shall be detained in custody) and 9(4) (entitlement to take proceedings before a court which decides without delay on the lawfulness of the detention). Supports Art. 14(1): “All persons shall be equal before the courts and tribunals”, with the right to a fair and public hearing by a competent, independent and impartial tribunal established by law, the closed grounds on which press and public may be excluded, and the rule that judgment shall be made public except where the interest of juvenile persons otherwise requires or the proceedings concern matrimonial disputes or the guardianship of children. Supports Art. 14(3)(e) (“To examine, or have examined, the witnesses against him and to obtain the attendance and examination of witnesses on his behalf under the same conditions as witnesses against him”), 14(3)(f) (free assistance of an interpreter) and 14(3)(g) (“Not to be compelled to testify against himself or to confess guilt” — note that the Covenant adds the confession limb, which the European Convention text does not contain). Supports Art. 14(5). VERIFIED NEGATIVES from exhaustive search of the Covenant text: “proportion” occurs zero times, “equality of arms” zero times, and “remain silent” zero times. This is treaty text binding states party to it; it is not evidence of any state's domestic law, and the corpus invariant forbidding a treaty from standing in for a country applies to it.
Police and Criminal Evidence Act 1984 (1984 c. 60)
The National Archives (legislation.gov.uk) · Legislation · 1984 · link verified 2026-08-10
The official revised text of the Act, read directly at its table of contents, which sets out its Parts: powers to stop and search (Part I), powers of entry, search and seizure (Part II), arrest (Part III), detention (Part IV), questioning and treatment of persons by police (Part V), and codes of practice (Part VI). Cited on this platform for ONE purpose: as a worked example that police powers are conferred and bounded by a named domestic statute with associated codes of practice, rather than existing as general authority. It supports the existence and structure of that statute in England and Wales. It supports nothing about Scotland or Northern Ireland, which have separate arrangements, and nothing whatever about any other country — it appears precisely to show that these thresholds are jurisdiction-bound.
United Nations Office on Drugs and Crime (Education for Justice) · International organisation · link verified 2026-08-10
The UNODC teaching module on police accountability mechanisms, read directly. Supports UNODC's own conceptual framework of accountability 'before, during and after the act' (ex-ante, ongoing and ex-post oversight); that internal control within the police service is the first degree of control in any police accountability system and works both preventively and reactively; that legal provisions alone are often insufficient for the day-to-day exercise of police powers, so services need comprehensive professional standards and codes of conduct giving practical guidance — the module's own worked example is guidance on arrest and detention procedures; and that because officers hold wide discretion and meet ethical dilemmas (the module instances bending laws for perceived greater law-enforcement objectives, and deceptive interrogation tactics used to extract a confession) services also need a code of ethics built on impartiality, fairness, equality, justice and honesty. Describes how accountability systems are DESIGNED. It does not establish that any particular system works, and no effectiveness or public-trust claim on this platform rests on it.