The exclusionary rule is an established legal principle that forbids illegally obtained evidence to be used against any accused person. This legal notion first circulated in the English courts in the late 18th century but received its fullest expression in the seminal US case Mapp v Ohio where the Supreme Court disallowed police from admitting evidence they had taken by force. Until recently the status of the exclusionary rule in Ireland was somewhat ambiguous with lower courts espousing the view it did not apply under the Proceeds of Crime Act 1996. The Supreme Court however has changed all that.

The CAB obtained €20,000 in cash from the dwelling of Michael Murphy Junior, on the basis of a warrant conducted under s.29 of the Offences Against The State Act 1939. One flaw in this move however was the fact that that particular section has been ruled to be unconstitutional since the case of Damache v DPP. Both Murphy Sr and Jr attempted to argue this point to forbid the evidence being exhibited in court but the High Court and the Court of Appeal dismissed this claim. Yet a unanimous Supreme Court has allowed their appeal. Justice O’Malley took a purposive stance on the rule. She outlined how the aim of the rule is not to benefit defendants in criminal trials but has a broader purpose. It is there to ensure that constitutional rights are respected, and the administration of justice is applied in a way that displays integrity. O’Malley J also argued that this principle was not just confined to criminal proceedings as evidenced by past authorities such as Trimbole, State (Quinn) v Ryan, and CRH plc v Competition and Consumer Protection Commission. O’Malley J also interestingly said that a grossly negligent breach will give judges a discretion to refuse evidence (however there is a presumption in favour of doing so). The judge must consider if this was a breach so flagrant in violation that it warrants dismissal of evidence. The Court finally held that as this evidence was obtained in a way that outwardly showed disregard for both of the defendants’ rights, the appeal should be allowed.

This decision is emblematic of the double-edged nature of the exclusionary rule. While it does play an important role in respect the due process of justice, it can also hinder cases against criminals. Benjamin Cardozo famously remarked ‘The criminal is to go free because the constable has blundered,’. An indestructible principle of law is that justice must give equality to both sides. The Supreme Court’s decision appears to intend this for Murphy Jr and Sr. However it remains to be seen if this rebalancing of the scales will accrue more favour to criminal defendants than is deserved.

Daniel Forde – Law Editor