Section 78
PACE Explained
The Definitive 2026 Manual on the Exclusion of
Unfair Evidence and Procedural Law in England & Wales.
The Judicial Kill-Switch
Fairness as a
Constitutional Guard.
Section 78 of the Police and Criminal Evidence Act 1984 grants the judiciary the discretionary power to refuse prosecution evidence if its admission would fundamentally damage the fairness of a trial.
This is the primary check on State power in the High Court. It ensures that the police cannot benefit from breaking their own rules — specifically the PACE Codes of Practice — turning procedural errors into evidential liabilities for the Crown Prosecution Service.
01. The Purpose
of Section 78
Before 1984, the English legal system relied on common law discretion (the Sang principle) to admit almost all relevant evidence, regardless of how it was obtained. Section 78 was introduced to formalize judicial oversight, ensuring that the integrity of the justice system is not sacrificed for the sake of a conviction.
The Judicial Mandate
Judges are No longer passive observers of police conduct. Section 78 requires them to act as gatekeepers, weighing the weight of the evidence against the 'moral cost' of admitting it when it was seized or obtained unfairly.
The Balancing exercise
Discretion does not mean automatic exclusion.
Statutory Decomposition
02. The Statutory Test
"In any proceedings the court may refuse to allow evidence on which the prosecution proposes to rely to be given if it appears to the court that, having regard to all the circumstances... the admission of the evidence would have such an adverse effect on the fairness of the proceedings that the court ought not to admit it."
Adverse Effect
Does the way the evidence was gathered undermine the core machinery of a fair trial? This includes breaches of Code C (legal advice) which directly impact the defendant's ability to answer the case.
Judicial Discretion
The test is No-one of 'good faith' but of 'fairness'. Even if the police thought they were following the rules, the court must exclude if the result is a fundamentally unfair trial environment.
03. High-Impact
Exclusion Scenarios
Section 78 is No-one triggered for minor technical errors. It is aimed at substantial breaches that create an evidential imbalance.
Unlawful Stop Search
Searching without 'GOWISELY' or reasonable suspicion often leads to found items (drugs/weapons) being excluded.
The solicitor Trap
Denying contact with legal advice before an interview is a 'Tier 1' breach of Code C and Section 78.
Oppressive Custody
Excessive detention intervals or denying sleep renders resulting statements 'unfair' by judicial definition.
Digital Overreach
Searching phone data beyond the scope of a warrant or suspicion threshold.
The Exclusion logic Flow
Police Breach
Serious violation of PACE/Code
Fairness Impact
Admission creates imbalance
Judicial Discretion
Judge weighs circumstances
EVIDENCE EXCLUDED
Case viability impacted
Jurisdictional Distinctions
Section 78 vs Abuse
Evidential
Targeted
Section 78 acts as a scalpel. It removes specific unfair evidence from the jury's sight. The trial continues with the remaining prosecution material.
Systemic
Shutdown
Abuse of Process acts as a sledgehammer. It 'stays' the entire trial, permanently, because allowing the case to proceed at all would be a scandal to justice.
The Procedural Anchor
Driven by the
PACE Codes
To understand whether Section 78 will trigger, you must first master the PACE Codes of Practice. These are the statutory rules that define what a "fair interaction" looks like on the street and in the custody suite.
09. Judicial
Case Law Principles
The interpretation of Section 78 has been refined through decades of high-level appellate rulings. The Court of Appeal remains reluctant to exclude material unless the breach is qualitatively significant.
The 'Bad Faith' Factor
Case law increasingly emphasizes deliberate bad faith. Evidence found through a mistake in good faith is far more likely to be admitted than evidence secured through an intentional 'procedural shortcut' to bypass suspect rights.
1. Courts are the ultimate arbiters of admissibility, and their decision-making is heavily influenced by the severity of the breach. A single technical error in search protocol is rarely enough to exclude a weapon found during that search.
2. However, where multiple 'minor' breaches combine to create a general climate of unfairness, the court is increasingly likely to intervene under Section 78 PACE.
3. Section 76 (Confessions) and Section 78 (General Evidence) often overlap. A confession that survives Section 76 may still be excluded under Section 78 if obtaining it created an overall unfair trial environment.
Judicial Manual FAQ
Fairness
Intelligence
What is Section 78 PACE?
Section 78 of the Police and Criminal Evidence Act 1984 is a judicial power that allows a court to exclude prosecution evidence if its admission would have an adverse effect on the fairness of the proceedings. It is the most significant statutory protection against improper police conduct in England and Wales.
What does exclusion of evidence mean?
Exclusion of evidence means that the court refuses to allow the prosecution to present a specific piece of evidence to the jury (or for the Magistrate to consider it). The evidence is effectively 'thrown out' of the trial, even if it is otherwise reliable or proves the defendant's guilt.
Does an unlawful search mean case dismissed?
Not automatically. While an unlawful search constitutes a breach, Section 78 is discretionary. The court must decide if using the evidence found during that search would make the trial unfair. If the remaining evidence is strong enough, the case can proceed even if the specific search evidence is excluded.
Can evidence be excluded if police break rules?
Yes. Breaches of the PACE Codes of Practice (such as failing to follow GOWISELY or Code C interview safeguards) are the most common grounds for a Section 78 application. However, the breach must be serious enough to impact the fairness of the trial.
What is unfairness test?
The unfairness test is the judicial process of balancing the public interest in convicting criminals against the need for procedural justice. The court asks whether the way the evidence was obtained (e.g., through deception, oppression, or serious illegality) would compromise the integrity of the justice system if admitted.
What is adverse effect?
An 'adverse effect' occurs when the admission of evidence would undermine the defendant's right to a fair trial. This is often triggered when evidence is obtained in a way that deprives the defendant of a mandatory safeguard, such as the right to legal advice or the caution.
What is abuse of process?
Abuse of process is a wider legal doctrine than Section 78. While Section 78 excludes specific evidence, an 'abuse of process' stay stops the entire trial from proceeding, usually because it would be an affront to the public conscience to allow the case to continue due to extreme police/prosecutorial misconduct.
What happens if police breach Code C?
Breaches of Code C (detention and questioning) are treated seriously. Failing to provide a solicitor or an Appropriate Adult, or not allowing sufficient rest, can lead to any resulting confession or interview evidence being excluded under Section 78 or Section 76 PACE.
Can phone evidence be excluded?
Yes. If police search a phone without consent, a warrant, or a valid secondary statutory power, the extraction of that data may be deemed a serious breach of privacy and procedural law, leading to exclusion under Section 78.
Does Section 78 apply to terrorism cases?
Yes. While terrorism investigations are governed by Code H (which allows for extended detention), the fundamental protection of Section 78 PACE still applies to ensure that even in high-stakes national security cases, the trial remains fair.
Can confession be excluded?
Yes. Confessions can be excluded under Section 76 (if obtained by oppression or in unreliable circumstances) or Section 78 (if obtaining the confession was unfair, such as by denying legal advice).
Who decides exclusion?
The Judge (in a Crown Court) or the Magistrates (in a Magistrates' Court) decides Section 78 applications. In a Crown Court, this usually happens during a 'voir dire' (a trial within a trial) without the jury present.
Can prosecution appeal exclusion?
Yes, the prosecution can sometimes appeal a judge's decision to exclude evidence under 'terminating ruling' legislation, provided they certify that the exclusion makes the case effectively impossible to win.
Does breach mean compensation?
Not via Section 78. Section 78 only affects the criminal trial. For compensation, the individual must bring a separate civil claim for assault, trespass, or false imprisonment, usually in the County Court or High Court.
What is Section 76 PACE?
Section 76 is a mandatory exclusion power specifically for confessions. Unlike the discretionary Section 78, Section 76 *requires* a court to exclude a confession if it was obtained by oppression or in circumstances likely to make it unreliable.
What is oppressive questioning?
Oppression is defined by Section 76(8) and includes torture, inhuman or degrading treatment, and the use or threat of violence. In practice, it also covers sustained, aggressive, or coercive bullying during interviews that 'breaks' the suspect.
Can court ignore minor breaches?
Yes. Technical, minor, or 'good faith' errors by the police that do not significantly disadvantage the defendant frequently result in the evidence being admitted despite the breach.
What is reliability test?
While Section 78 focuses on *fairness*, reliability is a key factor. If a breach makes the evidence (like a confession) untrustworthy, it is almost certain to be excluded. However, even 'reliable' evidence (like a found weapon) can be excluded if the breach was serious enough to offend justice.
Does it apply in magistrates court?
Yes. Magistrates have the same duty as Crown Court judges to apply Section 78. They must determine if the evidence is admissible before reaching a verdict on guilt or innocence.
Can body cam failures affect case?
Yes. If police deliberately fail to record a search or interview in breach of force policy or PACE codes, it creates a 'secondary breach' that can support a Section 78 application by casting doubt on the officer's account of the interaction.
Can unlawful arrest void evidence?
Indirectly, yes. If an arrest is unlawful (breach of Code G), then any subsequent search (Section 32) or interview statement may be challenged under Section 78 as being the 'fruit of a poisonous tree'.
Is Section 78 discretionary?
Yes. The word 'may' in the statute gives the judge a choice. There is No automatic exclusion rule in English law (unlike the 'Exclusionary Rule' in the USA).
Does it apply before trial?
Section 78 applications are usually made during pre-trial hearings or at the start of the trial. Resolving these issues early helps determine which evidence the jury will actually hear.
Can defence apply anytime?
A defense lawyer can raise a Section 78 objection the moment the prosecution attempts to introduce the evidence. However, they are expected to serve notice of such applications well in advance of the trial.
What is fairness in criminal trial?
Fairness is a broad concept covering the right to be tried by an impartial tribunal, the right to legal representation, the right to silence, and the assurance that the state followed its own rules when collecting evidence against the citizen.
Authority Mastery
Deep-Dive Into The Procedural Safeguard Stack
Section 1 PACE
Foundational search power
GOWISELY Flow
The mandatory checklist
Strip Search Law
High-threshold protections
Use of Force
Absolute physical limits
Section 23 Drugs
Narcotics search power
Phone Search
Privacy & RIPA Rules
Arrest Guide
Necessity & Thresholds
PACE Codes
The Definitive Core Manual