Espoo Convention

The Convention on Environmental Impact Assessment in a Transboundary Context, signed in Espoo, Finland on 25 February 1991 and entered into force on 10 September 1997, is a regional treaty negotiated under the auspices of the United Nations Economic Commission for Europe (UNECE). It obliges parties to evaluate the environmental impact of certain activities at an early planning stage and to notify and consult affected neighboring states before a decision is authorizing the activity.

The convention applies to listed activities in Appendix I — including oil refineries, nuclear power stations, large chemical installations, motorways, major pipelines, large dams, and certain mining and waste operations — that are likely to cause significant adverse transboundary impact. The "Party of origin" must notify any "affected Party" as early as possible, share documentation, allow the affected public to participate, and take the consultations into account in the final decision. Disputes can be referred to an Implementation Committee, a notable feature of UNECE environmental governance.

Two protocols extend its reach:

• The 2003 Kyiv Protocol on Strategic Environmental Assessment (SEA Protocol), in force since 2010, pushes assessment upstream to plans and programs, not just individual projects.
• Amendments adopted in 2001 and 2004 open the convention to accession by UN member states outside the UNECE region, though entry into force of the second amendment was delayed.

The Implementation Committee has issued findings of non-compliance in several high-profile cases, including Ukraine's Bystroe Canal project in the Danube Delta and the lifetime extension of nuclear reactors. Espoo procedures have also featured in disputes over Nord Stream, the Belarusian Astravets nuclear plant, and the UK's Hinkley Point C. The convention is widely regarded as the foundational instrument codifying the customary duty, articulated by the ICJ in Pulp Mills (2010), to conduct transboundary environmental impact assessment.