Where a development proposal falls within one of the 'Schedule 2' categories in the Environmental Assessment Regulations, the developer must seek a screening opinion from the local planning authority. The authority will consider whether the development proposal would be likely to have significant effects on the environment. If the opinion is positive, the developer must carry out and submit an environmental impact assessment. If the opinion is negative, no such assessment is required.

Developers have tried to divide a project into parts, each of which would either not trigger the thresholds in Schedule 2 (and therefore not require a screening opinion), or would produce a negative opinion because the environmental effects of the development would not be significant.

The European and domestic courts have found this to be unlawful.

In R (on the application of Burridge) v Breckland District Council the claimant alleged that a developer had tried 'salami slicing' its original proposal for an anaerobic digester to produce biogas and a combined heat and power (CHP) plant which converts the biogas into electricity. The original proposal was for a single site. A second application was made for the digester to be built on the original site but for the CHP plant to be moved to a second location, linked to the first by an underground pipeline.

The court found that the two sites were interdependent and that the change was at least in part prompted by objections of the parish council. This was not a case where the developer had intentionally divided the development to avoid environmental assessment.

A second point arose from the claimant's allegation that the authority had failed to properly deal with the environmental impact of the second proposal and in particular the cumulative effects of development on the two separate sites. The authority had issued a negative screening opinion in the original application and in view of the small scale of the development of the CHP plant in the second proposal, no further screening opinion was issued.

The court held that the authority had carried out the procedures correctly in granting permission for both the original and the second applications. The authority was obliged to consider whether a proposal met the Schedule 2 criteria. Only if it did so would it be appropriate to take account of other sites in assessing the environmental impact of the proposal.