Written by senior criminal defence solicitors. Updated September 2026. Reading time about 12 minutes.
If you are facing a criminal investigation or charge, one of the first questions you will ask is what a criminal defence solicitor can actually do for you. The honest answer is that a criminal defence lawyer does not use a fixed collection of techniques to get someone acquitted. The proper defence depends on the evidence, the offence charged and the defendant's instructions.
What the prosecution must do never changes. The Crown must prove the offence to the required criminal standard, beyond reasonable doubt, and the defence can challenge any element that has not been proved. This guide sets out a comprehensive map of the defence techniques solicitors and barristers actually use in UK criminal cases, grouped into the three broad areas of denying the facts, challenging the legal elements of the offence, and testing how the evidence was gathered.
A good defence is not a checklist. It is a method. The prosecution carries the burden of proof and must satisfy the court of every ingredient of the offence to the criminal standard. Our job is to identify which parts of the Crown's case genuinely hold up and which parts do not. We then test the weak points, whether that means denying the facts, arguing the law, or challenging how the evidence was obtained.
In practice we group our work into three broad areas: defences that deny or explain the factual case, challenges to whether the legal elements of the offence itself have been made out, and procedural challenges to how the evidence was gathered. The sections below walk through each one in detail.
These are cases where the defendant says the prosecution's factual case is wrong. The defence can challenge the facts at almost every level:
The underlying principle is simple: suspicion is not the same as proof. Where the facts are disputed, the defence role is to find the gap between what the police assume and what the Crown can actually prove.
Sometimes the events themselves are largely accepted, but the prosecution cannot prove all the ingredients of the particular offence. A solicitor or barrister may argue that the Crown cannot establish:
This matters because proving suspicious behaviour is not enough. The prosecution must prove the elements of the offence actually charged. If even one essential ingredient is missing, the charge cannot be made out.
Where the facts and the offence are both engaged, a recognised legal defence may apply. These defences are tightly controlled by statute and case law, and their availability depends entirely on the circumstances.
Self-defence can arise where reasonable force was used to protect yourself or another person. The defence will normally examine what the defendant honestly believed was happening, whether force was necessary, the degree of force used, and whether the defendant acted defensively rather than unlawfully. The circumstances are considered as the defendant believed them to be. Section 76 of the Criminal Justice and Immigration Act 2008 contains important statutory provisions concerning reasonable force.
Reasonable force can also potentially be justified when preventing crime or assisting in the lawful arrest of an offender. This is related to self-defence but can arise in different factual circumstances.
Duress may apply where a defendant says they committed an offence because they were subjected to sufficiently serious threats. It is a tightly controlled common law defence and is not available for every offence. Important issues include the nature of the threat, whether there was a reasonable opportunity to escape it, and the connection between the threat and the offence.
This is closely related to ordinary duress but concerns pressure arising from dangerous circumstances rather than simply a direct instruction from another person. Again, its availability depends heavily on the offence and the facts.
Automatism concerns genuinely involuntary conduct. Specialist medical evidence may become important because the court needs to distinguish true automatism from situations where the defendant simply cannot remember what happened.
The legal defence of insanity is highly technical and is different from an everyday understanding of mental illness. Expert psychiatric evidence may be required, and lawyers must consider the legal test rather than relying simply on the existence of a medical diagnosis.
A genuine mistake about facts can sometimes mean that the defendant lacked the state of mind required for an offence. Whether the mistake provides a defence depends on the particular offence.
Many offences require the prosecution to establish a particular intention. The defence may accept that something happened but argue that the defendant did not have the criminal intention required for the offence charged.
Some offences require proof that the defendant knew a particular fact or circumstance. The defence can therefore focus on whether the prosecution can actually prove that knowledge.
Consent can be legally relevant to certain offences, although there are significant restrictions on when consent constitutes a defence. The precise rules depend on the alleged offence and the circumstances.
A large part of criminal defence work involves testing how the evidence against you was obtained. Under the Police and Criminal Evidence Act 1984 (PACE), there are powerful mechanisms for challenging and excluding evidence.
The police interview can become an important part of the prosecution case. Defence lawyers may examine whether the correct caution was given, whether the suspect understood it, and whether access to legal advice was properly provided. They will look at whether questioning complied with PACE, whether an appropriate adult should have been present, and whether interview records are accurate and reliable. They will also test whether admissions are reliable and whether anything said was taken out of context.
A confession is not automatically conclusive proof of guilt. Section 76 of the Police and Criminal Evidence Act 1984 contains specific provisions concerning confession evidence. Questions can arise over oppression and circumstances affecting the reliability of a confession.
Section 78 of PACE provides an important mechanism concerning prosecution evidence. The court may refuse to allow evidence where, considering all the circumstances, admission would have such an adverse effect on the fairness of proceedings that it ought not be admitted. This can become highly important where there have been serious procedural problems.
Defence lawyers can examine how evidence was obtained, including police searches, searches of premises, stop and search, seizure of property, mobile phone evidence, computer evidence, interviews and surveillance evidence. An irregularity does not automatically make evidence inadmissible; the legal consequences depend on the circumstances and the applicable rules.
For more detail on your rights in these situations, see our guides on can the police search my car without a warrant?, police stop and search rights and police warrants in the UK.
Modern cases frequently turn on scientific, digital or identification evidence that can appear very persuasive at first glance. Careful analysis can reveal assumptions, gaps and alternative explanations.
Independent experts may be instructed where appropriate to examine prosecution forensic evidence. Areas can include DNA evidence, fingerprints, toxicology, medical evidence, digital forensics, handwriting, financial records and accident reconstruction. The objective is not merely to find an expert who disagrees with the prosecution; expert evidence must satisfy the applicable evidential requirements.
Modern criminal cases frequently depend heavily on digital evidence. Defence teams may examine mobile phone extraction, messages, emails, CCTV, location information, metadata, computer records, social media material and deleted data. They will test whether a device can actually be attributed to the defendant, whether someone else had access to an account or device, and whether the prosecution's interpretation of the digital evidence is accurate.
For questions about your own digital footprint, see do I have to give the police my mobile phone passcode?
CCTV can appear convincing but still require careful analysis. The defence may investigate timing, image quality, continuity, identification, missing footage and whether the footage actually supports the prosecution's interpretation.
Where identification is disputed, defence lawyers may examine the circumstances in which the witness saw the alleged offender and whether proper identification procedures were followed. Factors such as distance, lighting, duration and previous familiarity can become important.
Where a case reaches trial, the defence uses a range of advocacy and legal techniques to test the prosecution case before the court.
Cross-examination is a central part of trial advocacy. A barrister or solicitor advocate may test accuracy, reliability, memory, inconsistencies, previous statements, the ability to observe events, motive, bias and contradictions with objective evidence. The purpose is to test evidence fairly and expose weaknesses relevant to the issues the court must decide.
The Criminal Justice Act 2003 regulates when hearsay evidence may be admitted in criminal proceedings. Defence lawyers can examine whether the statutory requirements for admission are satisfied and, where appropriate, oppose its admission or challenge the weight placed upon it.
The prosecution may sometimes seek to introduce previous convictions or other alleged misconduct. The Criminal Justice Act 2003 contains detailed rules governing bad character evidence. Defence lawyers can oppose applications where the statutory requirements are not satisfied or where exclusion is legally justified.
Disclosure can be crucial. The defence may seek material held by investigators that could reasonably undermine the prosecution case or assist the defence. This can include material that was not initially relied upon by the prosecution.
A defence expert may identify weaknesses in methodology, assumptions, data, testing, interpretation, statistical conclusions and the limitations of the evidence. Counsel can then test the prosecution expert's conclusions through cross-examination.
In exceptional circumstances, the defence may ask the court to stay proceedings as an abuse of process. These arguments are legally complex and can concern situations where a fair trial is no longer possible or where proceeding would offend the court's sense of justice and propriety.
At the appropriate stage of a trial, the defence may submit that the prosecution evidence is legally insufficient for the case to continue. If the court accepts a submission of no case to answer, the relevant charge can end without requiring the defence to establish its own positive case.
A strong defence is not only about attacking the prosecution case. It is also about presenting your own evidence, and about engaging with the prosecution and the court in the right way.
Sometimes the strongest defence is demonstrating that apparently suspicious evidence has an innocent explanation. The prosecution may rely on possession, communications, financial transactions or association with another suspect. The defence may present evidence showing a legitimate explanation.
A prosecution does not necessarily need direct evidence; circumstantial evidence can establish guilt. However, the defence can examine whether individual pieces of circumstantial evidence genuinely support the prosecution's conclusion or whether reasonable alternative explanations remain.
The defence may identify witnesses capable of supporting an alibi, the defendant's account, the chronology, ownership or possession issues, relevant communications or other disputed facts.
Useful evidence can include legitimate records such as receipts, bank records, employment records, travel records, emails, contracts, photographs, medical records and business documentation. Any collection and use of evidence should be lawful and handled appropriately.
Where appropriate, a solicitor may make representations concerning the evidence and whether proceedings should continue. The precise approach depends on the investigation and the procedural stage.
The Crown Prosecution Service applies the Code for Crown Prosecutors when deciding whether a prosecution should proceed. Defence solicitors can sometimes make representations about evidential weaknesses or other matters relevant to a charging or continuation decision.
Where a defendant accepts criminal responsibility, the issue may not be whether they committed any offence but precisely what offence and on what factual basis. Lawyers may address whether the charge properly reflects the admitted conduct. This must always reflect the defendant's genuine instructions and the evidence.
Where guilt is admitted but important factual allegations are disputed, a formal basis of plea may identify the factual basis on which the defendant accepts guilt. If a material disagreement affecting sentence cannot be resolved, the court may need to determine the facts.
A Newton hearing may take place where a defendant has pleaded guilty but there is a significant factual dispute between prosecution and defence that could materially affect sentence. The judge hears evidence and determines the disputed facts.
Where a defendant accepts responsibility or is convicted, the defence role changes but remains important. Careful work at this stage can materially affect the sentence imposed.
This is not a defence to the charge, but it is an important part of criminal representation where guilt is accepted. Under the current Sentencing Council guideline, an indication of guilt at the first stage of proceedings can ordinarily attract a maximum reduction of one third. The available reduction decreases as proceedings progress. Importantly, the Sentencing Council expressly states that the guideline should not be used to pressure a defendant into pleading guilty.
Where someone pleads guilty or is convicted, the defence role changes significantly. A solicitor and barrister may present mitigation concerning personal circumstances, genuine remorse, previous good character, rehabilitation, age and maturity, caring responsibilities, employment, relevant health circumstances, cooperation, steps taken since the offence and a low risk of further offending. Mitigation and guilty plea credit are separate considerations under the sentencing framework.
Where legally relevant, evidence concerning a defendant's character may assist the defence or the sentencing case. The usefulness and admissibility of such evidence depend on the circumstances.
After conviction or sentence, lawyers can advise whether there are proper grounds to challenge a conviction, a sentence or particular legal rulings. An appeal is not simply another opportunity to retry the case because the defendant disagrees with the result; there must be proper grounds to challenge the decision.
Understanding how a defence is built starts with one step: getting the right advice early. The sooner a specialist solicitor is involved, the sooner we can protect your rights, challenge the evidence and build the strongest defence for your case. You do not need to face this alone.
If you are in custody, ask the custody officer to contact us for free police station legal advice, or call our 24 hour emergency line. Every case is different, but every client is entitled to a thorough and honest defence.
This guide is general information and not legal advice for your specific case. Speak to a qualified criminal defence solicitor about your own circumstances.