Every ordered system of criminal justice has to have rules concerning what information can be adduced as evidence in court proceedings. In our system these rules are promulgated by the common law and in recent years, increasingly by statute. These two systems have largely comfortably coincided. Whilst this is an oversimplification of their inter-relationship, generally the common law has formulated the general principles of admissibility whilst statute has determined rules for courts to follow which govern whether particular types of evidence should be admitted.
The overarching principle of the common law framework is that relevance is the cornerstone of admissibility. For example, in R v P  1 AC 146, the House of Lords held that unlawfully obtained information should not be deemed inadmissible just because it was so obtained. Whereas Parliament has intervened in a more targeted and discrete fashion. A good example of this are the guidelines enacted in the Criminal Justice Act 2003 concerning when a court should admit hearsay and bad character evidence and on whom the evidential burden rests.
S56 of the Investigatory Powers Act 2016 (IPA), which came into force on 27 June 2018, is another example of this interaction. It concerns information obtained by State eavesdropping (the statutory word is “interception”) of an individual’s telephone calls. What was overheard and recorded may be highly relevant and therefore probative of an accused’s innocence or, and far more likely, guilt. If so, the fruit of this intercept would almost certainly be usable in a criminal trial. S56 however intervenes and determines that insofar as intercept material obtained by a UK State agency is concerned, neither the prosecution nor defence can adduce it in any circumstances. Furthermore it proscribes any mention whatsoever of the existence of such material. Therefore, a criminal trial must be conducted on the basis that even if the material might exist and might go to the heart of the issues in dispute which a judge or jury must determine, it does not exist. Despite its potential relevance, Parliament has decreed that if it was obtained domestically it is beyond the bounds of what can be mentioned by anyone involved in criminal litigation.
This statutory exclusionary rule of both unprecedented and unique breadth has existed since 1985. S56 reiterates s17 of the Regulation of Investigatory Powers Act 2000, which in turn reiterated s9 of the Interception of Communications Act 1985. Despite the transformational changes in methods of surveillance during the last thirty years and the general public’s increasing awareness of the near ubiquitous surveillance of many aspects of daily life by either the State or private sector, it is said that this blanket ban is necessary. That if relaxed it would disclose a hitherto secret method of how law enforcement detects and investigates serious or organised crime. That hardened criminals would react to this disclosure by developing new and covert means of communicating with each other.
The utility of this exclusionary rule or ban has been the subject of prolonged controversy within law enforcement communities. The aim of this article is to provide a degree of enlightenment derived from two recent judgments as to this debate.
Bearing in mind the ban’s existence, it might be thought that it could never be the subject of litigation or of judicial consideration. However, the admissibility in criminal proceedings of material obtained as a result of intercepted phone calls was the subject of Virdee v NCA  EWHC 1119, which was decided by the Admin Court, and then R v Knaggs  EWCA 1863 by the Court of Appeal. The reason why this material was considered in both cases was because it had been obtained by a foreign law enforcement agency which had passed it to the National Crime Agency (NCA). The ban does not apply to such material.
In Virdee, the German police provided the NCA with six recordings and consequently the latter commenced a bribery investigation. It contended that they revealed compelling evidence of a plan to bribe politicians, including two prime ministers in several Caribbean states. Mindful that this was a JR application, not a trial, he held (para 86) that the material “was capable of giving rise to a reasonable inference that the claimants were willing in principle to make corrupt gifts”, and that the only issue of contention amongst the alleged bribers was that these politicians “were asking for too much.”
The excerpts which the Judge quoted in his judgment have led to a political furore in the Caribbean followed by ministerial resignations.
It is apparent from this judgment that had the ban applied to these recordings, there would never have been an NCA investigation. It would have prohibited the NCA from making any forensic use of them. The NCA was able to investigate only because the German police apparently had gathered them in connection with an unrelated tax fraud investigation which it was conducting.
In Knaggs, the telephone recordings were obtained by the Dutch police. Unlike in Virdee, the NCA knew and discussed with their Dutch counterpart in advance the deployment of this surveillance. The recordings proved to be probative, if not pivotal, evidence of a conspiracy to import a large amount of Class A drugs into England. The Crown Prosecution Service (CPS) wished to adduce them at trial.
The defendants submitted that the ban rendered them inadmissible based on two alternative submissions. Either because the interception was conducted by the NCA and had been made to appear it was done by the Dutch. Alternatively, they were made by the Dutch at the behest of the NCA. Had either submission succeeded, the ban would have applied and the CPS would have been unable to adduce this evidence. Obviously the ban applies as regards the first submission. It applies for the second because to procure the Dutch police’s assistance, the NCA would have had to have first sought the issuance of a domestic (English) interception warrant. However, after hearing extensive evidence from the NCA and the Dutch police, the trial judge held that the liaison between them did not result in the former making a request of the latter to conduct the recordings. The Dutch would have done this anyway; they were not prompted. There was thus no reason to believe that circumstances within the ambit of the ban had occurred. The judge made this determination notwithstanding that it appeared that prior to the recordings being made, the CPS and its Dutch counterpart had already resolved that the defendants would be prosecuted in England.
What lessons should be drawn from these two cases? First the ban can hamper the investigation and prosecution of serious crime. Supporters of the ban’s continuance would agree but would contend that secrecy is in the public interest because of a still lingering limited apprehension by organised criminal gangs (OCGs) that their telephone calls may be being listened to.
It is submitted that this contention is increasingly tenuous. OCGs must increasingly be taking precautions or counter-measures. Professional assassins tend to wear gloves and/or destroy their clothing knowing that it will be DNA tested if recovered. OCG experience of having members imprisoned in many other countries based on intercept evidence where a similar ban does not apply must be salutary. The excerpts quoted in the Virdee judgment reveal that the speakers reminded themselves that they ought to mainly speak “offline.” The fear is that the ban no longer serves any useful purpose. Moreover, inadvertently it can emasculate a putative prosecution when OCG members do accidentally slip up and make incriminatory remarks. Removing the ban would permit a prosecutor to decide whether or not to adduce such evidence. They would not be obliged to do so in every case. Furthermore if they elected not to do so, the duty to disclose unused material does not apply to that which is incriminatory of an accused. A PII application would be merited only if it was exculpatory.
Second, the ban is creating the conditions for noble cause corruption amongst UK law enforcement officials and dubious findings of fact by judges. As to the former, whilst there is no reason to believe that the NCA acted improperly in either of the above cases, the cases demonstrate that the ban is vulnerable to being gamed or circumvented by law enforcement. For example, that a foreign NCA equivalent can be inveigled to open an supposedly autonomous investigation of an NCA target for the purpose of having their telephone conversations lawfully recorded and then shared. The stark contrast between a UK absolutist ban versus a regulated system of admissibility which appears to be the norm elsewhere will inevitably encourage international law enforcement arbitrage. This anomaly encourages the nod and the wink or plausible deniability. Neither is desirable in criminal justice.
 In his judgment, Holroyde L.J. quoted extensively from the transcripts and they can be read there.