The Supreme Court delivered a landmark judgment in the case of DPP v JC  IESC 31 where it articulated a new exclusionary rule concerning unconstitutionally obtained evidence. Prior to this decision, the old long-standing exclusionary rule from the case of DPP v Kenny  2 1R 110 provided that unconstitutionally obtained evidence must be excluded, regardless of the degree of care exercised or the state of knowledge of those involved, unless there were “extraordinary excusing circumstances”.
The case of DPP v JC related to the criminal trial of Mr JC and the trial judge’s decision to exclude incriminating statements made by the accused as they had been unconstitutionally obtained. The circumstances of unconstitutionality in that case were that while the particular form of warrant used was valid at the time of its execution, a subsequent legal decision declared the section under which it had been obtained unconstitutional. The incriminating statements were thus, technically, unconstitutionally obtained evidence and, under the law as it then stood, had to be excluded from the trial. In excluding the tainted evidence, the trial judge was correctly applying the existing exclusionary rule from DPP v Kenny.
The State appealed the case to the Supreme Court where it sought a reconsideration of the exclusionary rule. A sharply divided Supreme Court, by a majority of four to three, observed that the old exclusionary rule effectively operated as an automatic absolute bar on the admissibility of unconstitutionally obtained evidence, save for the most extreme circumstances. This, they thought, went too far and did not strike a proper balance between the entitlement of society to have, on the one hand, those guilty of crime convicted, and of ensuring, on the other hand, that agents of the State operate within the legal boundaries of their investigative powers.
The Supreme Court went on to set out a new exclusionary rule, which permits the admissibility of unconstitutionally obtained evidence where the “unconstitutionality concerned arose out of circumstances of inadvertence or by reason of developments in the law which occurred after the time when the relevant evidence was gathered”. While acknowledging that the new test of inadvertent breach could be argued to “place a premium on ignorance”, the Court went on to confirm that the test goes beyond merely assessing the state of knowledge of those at the "coal face" but also requires an assessment of any supervisory officials materially involved in the process.
This enormously significant decision will have wide ranging implications particularly in the context of regulatory investigations such as dawn raids. Given the focus of the new test on the state of knowledge of those gathering the evidence, it will become all the more important to obtain legal advice at the earliest opportunity to assess the constitutionality of a dawn raid or search warrant so that any concerns in that regard can be advanced as appropriate.