## Facts

- The case concerned the approval process for the High Speed 2 (HS2) rail project and the application of Directive 2011/92/EU (the EIA Directive), which mandates environmental impact assessments for significant infrastructure.
- The claimants argued that the use of a hybrid bill in Parliament to approve HS2 did not comply with the EIA Directive’s procedural requirements, particularly regarding public participation and environmental review.
- The dispute arose over whether the UK's parliamentary process fulfilled both the public input and environmental analysis standards set out under EU law.
- The hybrid bill process is a traditional UK legislative method for large projects, enabling detailed review and feedback from affected parties.

## Issues

1. Whether Parliament’s approval of HS2 via a hybrid bill satisfied the requirements of Directive 2011/92/EU on environmental impact assessments, specifically regarding public participation and environmental review.
2. Whether EU law imposes limits on the UK Parliament’s legislative procedure, such that the hybrid bill process could be found insufficient under European law.
3. How UK courts should address legal challenges alleging that parliamentary actions have breached EU law standards for environmental protection and procedural rights.

## Decision

- The Supreme Court determined that the hybrid bill process, although distinct from the method envisaged by the EIA Directive, was compatible with EU law.
- It held that the EIA Directive does not mandate a specific legislative procedure for environmental assessment; member states may implement its objectives in a manner consistent with their constitutional arrangements.
- The Court affirmed that Parliament retains final authority in lawmaking, and the hybrid bill procedure ensures necessary public participation and environmental consideration.
- The claim that the hybrid bill process undermined the aims of the EIA Directive or breached EU standards was rejected.

## Legal Principles

- Parliamentary sovereignty remains fundamental; EU directives must be implemented in accordance with constitutional traditions, provided their core objectives are met.
- The EIA Directive requires thorough environmental review and public participation but does not prescribe exact procedural mechanisms.
- National courts must balance domestic constitutional principles with compliance to EU law, especially when reviewing legislation authorizing major infrastructure projects.

## Conclusion

The Supreme Court confirmed that the hybrid bill process for approving HS2 satisfied both UK constitutional principles and the requirements of the EIA Directive. This decision clarified the relationship between parliamentary sovereignty and EU obligations in the context of environmental assessment for large-scale infrastructure planning.

R (Buckinghamshire County Council) v Secretary of State for Transport [2014] UKSC 3