Environmental impact assessment (EIA) is an important part of consenting large infrastructure and other projects. Recent UK court decisions contain useful lessons.
Screening
Screening is the process of deciding whether EIA needs to carried out. Those carrying out screening will be reassured by Mrs Justice Lieven’s comment:
“.. a screening direction is a preliminary assessment rather than an examination paper expected to contain a record of each and every issue and each and every conclusion”
The examination paper analogy was apt in the recent case involving the redevelopment of the Wyndford flats in Glasgow. The first issue was the column heading in the opinion – “Is this likely to result in a significant adverse effect on the environment?”. At the screening stage, the Regulations do not refer to “adverse”. The first instance judge held the wrong test had been applied, but refused to reduce the opinion because application of the correct test would have produced the same result. On appeal, the Inner House went further, holding the opinion was not flawed:
“Nevertheless, again applying common sense in the context of the development under consideration, and most developments, it will be effects which are adverse to the environment which will be looked for.”
The second issue involved taking into account mitigation. The Inner House held that the extent to which mitigatory measures can be taken into account in a screening opinion will vary according to the circumstances. It “accords with common sense” to take into account mitigation which is part and parcel of the development.
Defining the project/ “salami-slicing”
There can be circumstances where a bigger project needs to be taken into account. The legal principle is that a development should not be considered in isolation if in reality it is an integral part of a more substantial development. That approach is to prevent a project avoiding EIA by being split into separate consent applications ("salami-slicing").
Application of that principle has led to much litigation. For example, in 2023 the Court of Appeal held that a bridge to nowhere could not be assessed as a standalone project. It noted the dangers of over-relying on other cases.
That comment was prescient. In 2025 another bridge reached the courts, but this time the judges upheld the decision that it was a standalone development, not requiring EIA. Although adjectives such as “integral”, “key” and “unlocking” were used to describe the bridge, that did not mean the wider development was contingent on it.
Rochdale envelope
The “Rochdale envelope” is a practical device used to address the situation where details of the project are not available at the initial consenting stage. It involves carrying out the EIA using defined parameters – the envelope – and the subsequent consent imposing conditions to ensure the project remains within those parameters.
For a new ferry terminal, the Rochdale envelope included a type of ship which doesn’t exist yet, because the terminal has a 50-year design life.
Other regulatory controls
The ferry terminal case is also a reminder that the EIA process can have regard to other regulatory controls. Although it was not possible to ascertain safe use by the maximum design vessel until it has been fully specified and designed, the Harbour Master confirmed that actual use by such a vessel would be prohibited until it was demonstrated that the vessel could manoeuvre safely in and out of the berths.
Lessons
The judges in the Wyndford case referred twice to using common sense. Does that show EIA is about “common sense”? That is perhaps going a bit too far, but the courts are taking a realistic approach, taking account of integral mitigation and the relevance of other regulatory controls, continuing to endorse use of the Rochdale envelope approach, and being reluctant to submit documents to detailed forensic examination.
[This blog is based on workshop sessions presented at the Scotland’s EIA Conference 2025]
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