Background
Friends of the Irish Environment and two individuals seek judicial review of the Environmental Protection Agency’s approval of drinking water from the Lee Road treatment plant operated by Uisce Éireann, despite repeated exceedances of the 50μg/l parametric limit for manganese. The applicants argue these exceedances violate the EU Drinking Water Directive and pose health risks, particularly to infants and children. Uisce Éireann opposes the challenge through affidavits from Professor John Fawell, a toxicologist and water science expert.
The applicants applied for permission to cross-examine Prof. Fawell on seven issues where they claimed his expert opinion conflicted with evidence from Professor Scally, a public health specialist they rely upon. The application was filed late in the proceedings—after opposition papers were served in April 2026 but before the hearing scheduled for 1 July 2026.
The Court’s Holding
Justice Emily Farrell denied the motion for cross-examination. She held that while cross-examination in judicial review proceedings is rare, it may be permitted where there is a genuine dispute in evidence that requires resolution to determine material issues in the case. However, the applicants failed to demonstrate such necessity here.
The court identified the controlling principle: cross-examination requires a genuine conflict of fact or expert opinion—not mere disagreement or denial—and resolution of that conflict must be essential to determining the legal issues. Bare contradictions, challenges to legal interpretations, inferences, and disputes over the application of legal principles (such as the precautionary principle) do not form a proper basis for cross-examination.
Examining each of the seven disputed issues, Justice Farrell found that most involved matters of legal interpretation rather than factual or expert disagreements. The dispute over what the precautionary principle requires, the meaning of the Drinking Water Regulations, the legal status of WHO Guidelines, and whether exceedances at particular concentrations pose health risks all involved legal questions unsuitable for expert cross-examination. While both experts acknowledged that epidemiological studies show manganese can cause neurological effects in children, the experts differed on the threshold level of concern—Prof. Scally relied on the statutory 50μg/l limit; Prof. Fawell opined that risks are unlikely below 120μg/l. However, this difference was rooted in competing legal and policy judgments about how to apply safety standards, not a factual dispute amenable to cross-examination.
Key Takeaways
- Cross-examination in judicial review is exceptional and requires a genuine, material dispute in evidence—not mere disagreement between witnesses or parties.
- Disputes over legal interpretation, application of statutes, and the meaning of regulatory principles (like the precautionary principle) are not proper subjects for expert cross-examination.
- An applicant must point to conflicting factual or expert evidence, not merely state disagreement with the respondent’s expert opinion, to justify cross-examination.
- Procedural delay in seeking cross-examination, while disfavored, does not automatically defeat an application if the court determines cross-examination is genuinely necessary.
Why It Matters
This decision clarifies the narrow scope of cross-examination in Irish judicial review proceedings. It establishes that applicants challenging administrative decisions cannot use cross-examination as a tool to probe or develop evidence on legal questions; the remedy is limited to resolving genuine factual disputes. This protects the efficiency of judicial review and prevents it from morphing into a full trial on underlying facts and law. For environmental and health advocates, the ruling means that disagreement with an expert’s threshold judgments about safety—even when those judgments involve competing interpretations of scientific data—will not ordinarily warrant cross-examination unless there is a clear factual conflict (e.g., disputed test results or methodology).
The case also underscores the significance of the precautionary principle in EU water law: while both parties accept that manganese poses health risks above certain levels, the court treated the question of what level triggers precautionary action as fundamentally a legal issue for the court to decide, not a matter for dueling expert testimony. This suggests Irish courts will resolve the scope and application of the precautionary principle through legal reasoning rather than via adversarial expert evidence.