Ross & Anor (Acting On Behalf of Stop Stansted Expansion) v Secretary of State for Transport

For the airport NSIP provisions, “capable” capacity means the increase realistically expected to be achieved from the proposed alteration. It does not require a hypothetical calculation using technically possible maximum figures. The statutory reference to what is “expected” requires an assessment grounded in the likely performance of the infrastructure. Planning caps may be disregarded when assessing capability, but relevant operational restrictions remain material.

Judicial review of decisions informed by scientific, technical or predictive material applies a substantial margin of appreciation. The court must examine whether the decision-maker explained and lawfully evaluated the material, but must not retake the decision or conduct its own technical appraisal. The section 35 discretion is broad, and an evaluative conclusion that a project lacks national significance will be difficult to challenge unless legally flawed.

The claimants, acting for Stop Stansted Expansion, sought judicial review of the Secretary of State for Transport’s decision that proposed taxiway links, aircraft stands and an increase in Stansted Airport’s passenger cap did not constitute an airport-related nationally significant infrastructure project under the Planning Act 2008.

The challenge concerned two routes to NSIP status. First, whether the works were an airport alteration expected to increase passenger capacity by at least 10 million annually under section 23. Secondly, whether the Secretary of State should have directed under section 35 that the development be treated as nationally significant. The hearing was a rolled-up permission and substantive hearing.

1. Outcome. Permission was arguable on both grounds, but the judicial review claim failed on the merits and was dismissed.

2. Section 23. The proposed taxiway improvements were capable of constituting an “alteration” under section 23(6). The statutory definition uses “includes” and was sufficiently broad to cover improvements to runway linkages designed to increase runway capacity. The different context of section 9(6) of the Land Compensation Act 1973 did not assist the construction.

3. The phrase concerning passengers for whom the airport “is capable” of providing services required a judgment about the capacity realistically achievable after the alteration. It did not require a speculative arithmetical exercise based on every technically possible maximum. The word “expected” in section 23(4) required an assessment grounded in the likely practical performance of the infrastructure. The Secretary of State was entitled to disregard planning caps when assessing theoretical infrastructure capacity, while treating existing night-flight restrictions as a material constraint.

4. The Secretary of State lawfully relied on projected passenger-per-aircraft figures, long-haul trends and a Gatwick comparison as a limited sense-check of hourly runway movements. The claimants’ criticisms sought to substitute the court’s assessment for the decision-maker’s evaluative judgment.

5. Technical and scientific material. Where a decision is informed by scientific, technical or predictive assessments, the court must not retake the decision or conduct its own technical appraisal. It may require a clear and accurate explanation of the relevant material, but must respect specialist expertise and the possibility of competing scientific views. The hurdle for irrationality is formidable.

6. Section 35. The power to direct that non-NSIP development be treated as requiring development consent is broad and discretionary. The Secretary of State was entitled to conclude that the proposal was not part of a wider NSIP, that the relevant carbon impacts fell within the lawful “making best use” policy, and that the economic benefits were important but largely local. Reliance on the policy and its national forecasting model was not an unlawful disguised challenge to the decision.

7. The conclusions under section 35 were reasonable and legally open to the Secretary of State. Both grounds were dismissed.