Why do the police arrest?

Orla Slattery, Senior Lecturer at NLS https://www.ntu.ac.uk/staff-profiles/law/orla-slattery

February 2026 saw two high profile arrests following the release of the most recent tranche of documents from the Epstein files. These are ongoing criminal investigations, and we cannot speculate on what led to these arrests or the likely outcomes.

We can though consider when and how the police arrest suspects, and the legality of such arrests.

Interviews under caution

During an investigation, police can interview a suspect regarding their suspected involvement in criminal offences. The purpose is to obtain evidence and question suspects to assist the investigation.

The interview must be recorded, and the suspect will be entitled to legal advice throughout. This interview will be conducted ‘under caution’ and in accordance with legislation to ensure fairness. The caution is familiar to anyone who has seen any crime dramas;

‘You do not have to say anything. But, it may harm you defence if you do not mention, when questioned, something which you later rely on in court. Anything you do say may be given in evidence.’ 

The caution should be given before asking the suspect any questions. It reminds the suspect of their legal right to silence, meaning that they can avoid providing evidence that implicates them in the offence. There is an important caveat, if they don’t mention in interview something that they wish to use in their defence at a subsequent trial, they may not then be believed.

Failing to give this caution could mean valuable evidence is lost, by way of becoming ‘inadmissible’ in court. The caution should ensure that suspects understand the relevance of questioning and therefore using what they said as evidence without it is unfair. Likewise, if not cautioned it would not be fair to assume that suspects understand the significance of refusing to answer questions.

The necessity to arrest

The police do not need to arrest a suspect to interview as this can be done on a ‘voluntary’ basis. In circumstances where the police do arrest a suspect, they need to consider If it is legally ‘necessary’ to do so.

The grounds for arrest must be that there is reasonable suspicion that the suspect has committed an offence and that the suspect needs to be detained. Police can arrest where it is necessary to:

·         ascertain a suspect’s name and/or address,

·         prevent a range of imminent consequences e.g. preventing injury (to the suspect/ others), damage to property and obstruction of a highway or preventing an offence against public decency

·         to protect children or vulnerable people.

·         to allow a prompt and effective investigation

·         to prevent the investigation being hindered by the disappearance of a suspect.

In cases where police arrest where there is an ongoing incident or threat of further disturbance, it will be straightforward to justify arrest. Similarly, where suspects may evade investigation by ‘disappearance’ it may be simple to justify an arrest.

In other cases, a commonly used ground is that of allowing a prompt and effective investigation. Guidance on this ground suggests that arrest is necessary to prevent the suspect contacting others, discussing matters with co accused(s), or destroying potential evidence. Arrest, for certain offences, gives the police wider search powers without a warrant, meaning a suspect’s property can be searched as part of an investigation. This also allows for ‘special warnings’ to be given that can influence evidence obtained by questioning.

What happens during the arrest

On arrest a suspect should be informed of the offence they are being arrested on suspicion of and be provided sufficient information so as to understand why they are being arrested. They should also be told why it has been deemed necessary that they are arrested, rather than dealt with voluntarily. They will be given the caution, and although they should not be questioned now, anything they say will be recorded, and potentially used as evidence.

After arrest they will be transported to a police station with a custody suite. Officers will present the suspect to a ‘custody officer’ - a police officer who is of at least the rank of sergeant. The officer’s grounds for arrest should be considered afresh by the custody officer, who is responsible for authorising detention and assessing any risk to the suspect whilst in custody, and ensuring that they are aware of their legal rights. Suspects are entitled to legal advice, and to inform a friend or relative of their arrest. Suspects may be searched on arrival, the custody officer will determine what property the suspect may keep with them, and what will be held by the custody officer for safekeeping until release. Anything with evidential value will be seized for use in the investigation.

Outside of interview and legal consultations, suspects will be detained in a cell, with access to a toilet and washing facilities. Suspects may also be entitled to drinks and meals, depending on the amount of time spent in detention.

A suspect’s lawyer will be given ‘disclosure’ from the police which should include enough information for them to understand why the police wish to ask questions but does not require the police to disclose any information that would compromise the investigation. The suspect will then be entitled to a private consultation with their lawyer so they can discuss the disclosure and the ramifications of police questioning.

The interview

The suspect will be reminded of the caution at the start of the interview. The suspect will be able to deal with the questioning in the following ways:

1.      Answer questions & admit the offence

This is an option taken by suspects who are aware there is overwhelming evidence against them and who wish to use their cooperation with the investigation as mitigation.

2.      Answer questions & deny the offence

This is an option usually taken when the suspect is confident that they are innocent of any wrongdoing, and that they are unlikely to change their account if matters proceed to court. Suspects can be caught out by this if the police have withheld evidence that contradicts the account they give.

3.      Remain silent AKA ‘no comment’

Contrary to popular belief, refusing to answer questions does not mean that a suspect is guilty. This may be a sensible option where the extent of the police evidence is unknown, and a suspect does not want to answer without a better idea of the evidence against them. It can also prevent a suspect from unwittingly providing police with evidence that they are missing e.g. confirmation of their presence at a certain location.

4.      Give a written statement

Instead of answering questions, a suspect can hand in a ‘prepared statement’ drafted in consultation with their lawyer, giving information regarding their defence without exposing them to the risk of difficult questioning. It is vital to anticipate and address police questioning with the statement, or a suspect may still appear to be evading difficult questions.

5.      Answer some questions but not others.

This will not be advised by any competent lawyer but may well happen when a suspect finds it difficult to maintain a ‘no comment’ interview. It is tactically a poor choice to pick and choose which questions to answer.

How long will a suspect be held in custody?

The standard maximum that a suspect can be detained in custody is up to 24 hours, although different limits apply in terrorism cases, and this can be extended in other serious cases. Detention should be reviewed to ensure it is still necessary at regular intervals by an inspector level officer.

There is no limit to the number of interviews that can be conducted during the suspect’s time in custody, but they should be offered rest breaks at two-hour intervals and on reasonable request.

When will a suspect be released?

This is dependent on the status of the investigation, and the final decision will rest with the custody officer, although advice on charge will usually be sought from the Crown Prosecution Service. The suspect will either be released and no further action taken, released whilst the investigation continues, or charged with an offence. If released, the custody officer will need to consider if bail conditions are ‘necessary’ to protect the suspect or others related to the investigation, to prevent further offending, or to prevent the suspect from failing to return to custody when required. Where the custody officer does not believe conditions are necessary, then a suspect will be ‘released under investigation.’

The consequences of an unnecessary arrest

The consequences of arresting someone unnecessarily are twofold. Firstly, there is risk that valuable evidence could be lost. If an arrest is unnecessary and is also held to be unfair any evidence gathered from the arrest of the suspect will not be useable in evidence, scuppering any chance of conviction.

Secondly, there is the risk that civil action will be taken against the police by the suspect resulting in compensation, along with the reputational risk to the police.

What is clear is that an arrest is not conclusive of guilt but whilst the investigation continues, as King Charles’ statement notes, ‘the law must take its course’.

Further Reading:

Police and Criminal Evidence Act 1984

PACE Code G