Staying Power: two important clarifications on abuse of process

In 2026, so far, the Court of Appeal has clarified two important points regarding the law of abuse of process. The first is how to consider whether the police’s failure to obtain relevant evidence has made a fair trial impossible, the second is the correct approach to considering whether the Court’s assessment of justice and propriety has been offended when the prosecution seeks to amend charges after conviction or sentence.

When the prosecution fails to get important evidence

It is almost trite law that if the investigator or prosecuting authority breach their duties to secure critical evidence and the resulting failure means that a fair trial is impossible, a case may be stayed as an abuse of process. This follows the first limb of abuse of process as articulated in R v Ng and O’Reilly [2024] EWCA Crim 493; the second being where the abuse amounts to an affront to the public conscience.

In R v HGF [2026] EWCA Crim 570, the Lady Chief Justice has reconfirmed the test to determine whether such a breach meets the threshold for an abuse of process and gives a clear example of how to apply it. But most notably, HGF is a case where the prosecution had other evidence capable of proving their case yet the serious prejudice caused by the police’s failure was incapable of being remedied meaning the trial was unfair.

In HGF, the prosecution failed to obtain CCTV footage despite agreeing to do so. Whilst the CCTV would not have captured the alleged sexual assault (which took place in a hotel room), it would have shown what the defendant and complainant were doing as they came into the hotel lobby. The footage was therefore important contextual evidence. At the Crown Court, the trial Judge stayed the prosecution because of the police’s failure despite there being other – perhaps more relevant – evidence, including that of the complainant.

The Court of Appeal described the key question as being whether the missing evidence was ‘important material by which the complainant’s credibility could be assessed’. In the Court’s judgment, what was critical was not the strength of the remaining evidence but the prejudice the defendant faced in being unable to challenge that evidence. The jury would have been left to speculate about what the missing footage showed. This simply meant a fair trial was impossible.

HGF therefore reconfirms the three-stage test from R v Dobson [2001] EWCA Crim 1606 at [34] for establishing whether a failure to obtain evidence has made a fair trial impossible. The three steps are:

1. What was the duty of the police in the circumstances?
2. Did the police fail in their duty in not obtaining and retaining the relevant material?
3. If so, was the prejudice suffered serious prejudice to the extent that no fair trial could be held in the light of such failure?

While every case and argument that there has been an abuse of process turns on its own facts (as is nearly always pointed out in the authorities) and must be a remedy of last resort, HGF suggests that the hurdle for demonstrating the serious prejudice that leads to the impossibility of a fair trial is not as difficult to surmount as generally thought. The missing evidence does not need to the most central and most relevant evidence there could be (here, for example, it was not CCTV footage from within the hotel room where the sexual assault took place).

For practitioners, this is a reminder that showing the effect of a failure is paramount to the argument and it needs to be linked directly to the trial’s fairness. This approach can overcome strong counter arguments, such as the strength of a prosecution’s case or the weight and relevance of the other evidence. This will be even more powerful when the defence can show that they made an important line of enquiry clear and accessible to the police and the police did nothing about it – potentially in bad faith. In such circumstances, the foundations have been laid to successfully argue that a fair trial is impossible and that the prosecution should be stayed.

When the prosecution seeks to prefer new charges late in proceedings

It has often been considered that the point of conviction marks the end of a defendant’s jeopardy for criminal liability arising the facts used to bring the prosecution. This argument is made applying the principle of autrefois convict. This is essentially a bar to someone facing more than one prosecution for the same thing, sometimes called double jeopardy, which has become entwined with the concept of abuse of process. But in this situation the coast is not clear. The Court may allow a prosecution to continue if the prosecution can establish special circumstances that justify doing so.

This carve-out has recently been confirmed in R v Donaldson [2026] EWCA Crim 441.

In January 2024, the defendant was charged with the summary-only of offence of careless driving. The facts could have justified a charge of dangerous driving but it was not charged. The defendant pleaded Not Guilty at their first appearance, and the matter was listed for trail. On the first day of trial in April 2024, the defendant changed their mind and pleaded Guilty.  In June 2024, the matter came back to Court for sentence. At the invitation of a District Judge, the prosecution laid an additional charge of dangerous driving. It was a new charge where the defendant remained convicted of careless driving. The defendant pleaded Not Guilty to the dangerous driving and elected trial at the Crown Court. At the Crown Court in October 2024, an application to stay the new proceedings for dangerous driving as an abuse of process was refused. The defendant then pleaded Guilty to dangerous driving. The earlier Guilty plea to careless driving was then vacated and the prosecution withdrew it as a charge.

The defendant appealed the decision not to stay the prosecution for dangerous driving as an abuse of process, citing the principle of autrefois convict, citing Cockburn LJ in Elrington from 1861 that “if a party accused of a minor offence is acquitted or convicted, he shall not be charged again on the same facts in a more aggravated form.” Further, it was argued that R v Canatar [2025] EWCA Crim 611 was a binding authority that had created whereby it was an abuse of process for additional charges to be brought after a person has pleaded guilty to a lesser charge in the Magistrates’ Court.

On appeal, the prosecution argued that the case was not akin to autrefois convict and that the principle from Elrington applies where, after final disposal in one trial, the prosecution seeks to try the defendant on another charge arising from the same or substantially the same facts.

 In reviewing the relevant authorities, Stuart-Smith LJ held at [35] that:

There is no rule of law that further charges may not be preferred after the moment of conviction, whether on a person’s plea of guilty or on conviction by a jury.

And at [22] that:

…it would be hard to justify an immutable black letter rule that, from the moment of conviction, it will be an abuse of the process to bring forward another charge on the basis of the same or substantially the same facts as the charge of which the defendant has been convicted. Instead, the nature of the principle calls for a focus on the facts of the particular case applying the touchstone of fairness and the avoidance of oppression.

Stuart-Smith LJ held that the test to be applied in such circumstances is the second limb of abuse of process: whether the court’s sense of justice and propriety was offended or confidence in the criminal justice system undermined. The further the first proceedings have progressed, the more likely it is to be arguable that preferring further charges would be an abuse of process. (At [31] and [35]). But he warned at [40] that a second limb abuse is rarely found: something out of the ordinary must have occurred before a criminal court may refuse to try a defendant charged with a criminal offence when that trial will be fair. As such, while it was inefficient to have not charged dangerous driving initially, the failure to do so was not an abuse of the Court’s process.

Importantly, it was also held that Canatar was intensely fact sensitive and did not lay down a rule that it is an abuse of process for additional charges to be brought after a person has pleaded guilty to a lesser charge in the Magistrates’ Court.

For practitioners, this serves as a reminder that clear advice needs to be given to defendants that sometimes a conviction does not necessarily guarantee the end of the matter.