The Criminal Justice System

If you or a loved one is facing a criminal allegation, you will find yourself charting what might be the unknown territory of the criminal justice system. Often it will be very different to what you expected or understood it to involve. Most people come into contact with the criminal justice system very rarely and their perception of it is usually based on the media’s portrayal, which can often be very different to the reality.

Everyone’s case is different and the law and procedure of the criminal justice system can be complex. The following guide is a simple overview of the system. It’s no replacement for proper legal advice, however, having an understanding of the process can provide some reassurance through what can be a very difficult and stressful time. Please also see my fact sheets.

Police Investigations

There are a variety of ways in which a person can learn they are under suspicion of committing a criminal offence. It may be a family member or another person tells them, or the first time they are aware is when the police make contact. It might even be a person was unaware the police were investigating an offence until their arrest.

If the police are conducting an investigation they will invariably want to interview those under suspicion and any interview will be under “caution”. This means it is a formal interview and anything said can be used against that person in court proceedings. There are no “off the record” conversations with police and although most of us would naturally want to answer questions it is important that a person seeks advice if under suspicion of a criminal offence.

Everyone has the right to independent legal advice at the police station. Asking for legal advice doesn’t mean that a person isn’t co-operating; it simply means they are exercising a basic right and are seeking independent advice from a qualified solicitor to advise them on the law, their rights and entitlements whilst under police investigation. What a person does or does not say to the police whilst under investigation can have a major impact upon a case at a later stage.

It is common for police to arrest a person under suspicion without notice, although any arrest must be necessary and justified. There may be good tactical reasons for the police to do so, such as preservation of evidence. Often police will want to conduct searches of property and may seize evidence. There are strict rules that govern such searches.

If arrested, a person will be taken to a police station and held in a custody suite. Being arrested means that a person is in the custody of police and are not at liberty to leave the police station. There are codes of practice that govern the way a person who is under arrest is treated and they have rights and entitlements, which must be explained to them. If under arrest a person is entitled to:

Independent legal advice.

Have someone informed of his or her arrest and detention.

Consult the Police and Criminal Evidence Act Codes of Practice – which govern how police treat someone detained in police custody.

Have their physical needs met.

A person cannot be held indefinitely at a police station. There are time limits as to how long a person can be kept in custody before they are released or charged. Usually the maximum amount of time for a person to be held is 24 hours. For serious offences this can be extended up to 96 hours. However, these are maximums and a person will not automatically be kept for the maximum. Whether a person’s continued detention is justified must be kept under regular review by a Police Inspector.

A decision can be made as to whether any charges are to be brought or a person released without any further action whilst they are still under arrest and detained at the station. The police can also release a suspect whilst the investigation is ongoing. Sometimes, this will be on police bail meaning that the person is subject to a condition that they must return to the police station at a required time and date. Other conditions of bail can also be imposed which may prohibit certain behaviour. The purpose of returning to the police station will be to find out what is happening with the police investigation. Those required to return might find that the investigation requires more time or they might be re-interviewed if new evidence has come to light. A decision may have been made to charge them or they might be informed that the investigation will go no further. There are limits on how long a person can be kept on police bail. Suspects can simply be released under investigation, meaning that the investigation is ongoing but there are no bail conditions attached or a requirement to return to the police station. ( See my factsheets above for more information).

Investigations can take time. It is often very difficult to predict how long an investigation will last. The police are under a duty to ensure an investigation is carried out expeditiously (with speed and efficiency). Once the investigation has concluded the police will generally refer the matter to the Crown Prosecution Service for advice on whether any charges should be brought. Police still have the power to drop an investigation without referring the matter to the CPS but most investigations are referred to the CPS for advice.

Arresting someone isn’t always necessary in order to ensure a person co-operates with an investigation. The law sets out when arrest is necessary. Often there are advantages to co-operating with an investigation and being interviewed under caution without being arrested. If attending the station voluntarily by appointment a person is free to leave at any time and their DNA and fingerprints will not automatically be taken and kept on the police database.

See my Factsheets for more information on police investigations.

Court Proceedings

If a person is charged by police or summonsed to attend court it is important they do not lose heart or believe that the criminal justice system is working against them. It simply marks the beginning of the court process and what underpins that is a simple principle – that the burden of proof lies with the Prosecution. That burden is high and unless guilt is accepted by the defendant (the person facing criminal proceedings), the Prosecution must make a court sure of the defendant’s guilt before they convict.

All cases start with a hearing in the Magistrates’ Court. At that point decisions will be made as to which court is the most appropriate to deal with the case, namely the Magistrates’ Court or the Crown Court. Some offences can only be dealt with by the Magistrates’ Court (summary offences) and some only by the Crown Court (indictable only). A lot of offences can be dealt with by either court (either way offences) and which is the most appropriate court depends on the nature of the case. Initially it is the Magistrates’ Court that will decide if it can deal with a case if it is an either way offence. If they retain the case a defendant has the right to elect trial by Jury at the Crown Court if they wish. The decision as to which is the most appropriate venue for the defendant and their case requires legal advice.

If a defendant pleads not guilty a trial will have to take place. If the trial takes place in the Magistrates’ Court then the hearing date will often be the next occasion they attend court and the trial will be before a District Judge or a panel of Magistrates. If the case is transferred for trial before the Crown Court there will usually be at least two hearing dates in the Crown Court before the trial takes place. Whereas a Judge will preside over the trial dealing with matters of procedure and law, only a Jury of 12 people can make decisions as to the facts of a case and whether a person is guilty or not guilty.

Before the trial takes place, the Crown Prosecution Service will serve on the defendant or his legal team the evidence in the case. The evidence will be the statements and exhibits the prosecution is relying on to prove their case.

If someone has provided a witness statement to the police and the prosecution wish to call them as a witness during the trial their statement has to be written down and served on the defence. The witness will then have to attend court during the trial and give live evidence under oath. If a prosecution witness has provided a statement and the evidence contained within it is agreed by the defence it can be read out at trial as opposed to that witness being required to attend Court.

Along with serving the evidence on which they rely, the Prosecution also have an obligation to tell the defence about any material they have which doesn’t form part of the case against the defendant. The test as to whether material should be disclosed to the defence is whether the material might undermine the prosecution case or assist the defence. The Crown Prosecution Service represents the state and therefore must be fair, independent and objective ensuring that justice is done. If you’d like to read more about this disclosure obligation please read my factsheet.

Throughout the proceedings prior to trial the defendant and his legal team will prepare the case for trial. This will entail analysing the evidence, taking detailed instructions from the defendant, identifying and talking to witnesses who might be able to assist the defence and undertaking general investigations that will identify evidence that may support the defence or undermine the prosecution case.

If however, a defendant pleads guilty, then sentencing will take place and there will be no trial. Sentence is always the decision of the Judge.

The Judge will require information about the offence and the person who has committed the offence before they sentence. Often sentence is adjourned to allow information to be gathered. The probation services may be asked to meet with a defendant to prepare a report, often called a pre sentence report to assist the Judge with sentencing. The Sentencing Council has produced sentencing guidelines for many criminal offences to assist the Court in determining the appropriate sentence and to improve consistency in sentencing.

For more information on the court process please see my Factsheets.


Children over the age of 10 can appear in criminal courts.  Any child or young person who has been charged with a criminal offence aged between 10 – 17 years of age will be sent to the Youth Court.

The Youth Court will usually be part of the local Magistrates’ Court but unlike the Magistrates’ Court it has been modified to take account of the person’s youth and they are not open to the public.   The Youth Court has greater sentencing powers and sentencing options than the  Magistrates’ Court and this is deliberate so that more offences can be dealt with by the Youth Court as is it specially adapted for young people and their needs. There are of course some cases that the court have to send to the Crown Court.  The aims of the youth justice system is to prevent offending by children and young people and the Youth Court must have regard to their welfare. For further information please see my fact sheets. 


If a defendant has been convicted or sentenced, advice should be sought on what routes of appeal are available and whether there is merit in pursuing such steps. This area of law is very complex.

If a person has been convicted before the Magistrates’ Court the usual method of appealing a conviction is to the Crown Court where there will be a rehearing of the original trial in the Crown Court before a Crown Court Judge and two lay Magistrates. If a defendant is unhappy with the sentence imposed by the Magistrates’ Court that sentence can be appealed to the Crown Court where it will be considered afresh.

If a defendant has been convicted of an offence in the Crown Court and doesn’t agree with the verdict of the Jury there is no automatic right of appeal. However, if it can be established that there are grounds to suggest the conviction is unsafe a written application can be submitted to the Court of Appeal asking for permission to appeal. Initially a single Judge will consider the merits of the application and decide if permission is granted for the appeal to be argued before the Court of Appeal. If the application is successful in reaching the Court of Appeal the trial will not be reheard. The Court will simply consider the arguments raised as to why the conviction is unsafe and make their decision as to whether they agree or not.

If a defendant has been sentenced before the Crown Court and disagrees with the sentence, permission of the single Judge must be sought to appeal the sentence. Only if permission is granted will the full court consider the arguments as to why the sentence was wrong to impose.

Time limits apply to lodging notices of appeal therefore it’s always best to seek advice quickly. However, an appeal can still be heard out of time.

In the Magistrates’ Court any application to appeal a conviction or sentence must be lodged no later than 21 days after the sentence being passed. With regards to the Crown Court, permission to appeal must be sought and the notice lodged not more than 28 days from the date of conviction (if appeal regarding conviction is sought) and not more than 28 days of the sentence (if appeal regarding the sentence is sought).

A court’s decision can also be reviewed by the Administrative Court, which is part of the High Court. However, the appropriateness of undertaking such reviews requires legal advice.

For more information see my Factsheet “ I’ve been wrongly convicted, how can I appeal?