Clear and legally binding rules prevent competent authorities from approving projects and plans that may cause irreversible damage to biodiversity unless they are justified by imperative reasons of overriding public interest.

Consequently, environmental impact assessment (EIA) and strategic environmental assessment (SEA) procedures should include biodiversity criteria and refer to relevant national, European and international policy documents, such as the Belgian Biodiversity Strategy, the EU Biodiversity Strategy 2030, the CBD and biodiversity-related conventions and agreements. In this context, the guidelines on the integration of climate change and biodiversity in EIA and SEA published by the European Commission (2013) under the EIA and SEA guidelines (see below) should be applied.

To promote participatory environmental policy, it is important to link strategic planning (impact assessment of plans and programmes related to the environment) with public participation, as required by European directives.

The Convention on Environmental Impact Assessment in a Transboundary Context (Espoo, 1991) and its protocol and amendments define the obligations of Parties to assess the environmental impact of certain activities at an early planning stage. It also establishes the general obligation of States to notify and consult each other on all major projects under consideration that may have a significant adverse transboundary impact on the environment.

The European legislative framework already provides for the assessment of the impact of projects and plans on biodiversity:

          - Environmental Impact Assessment Directive 85/337/EEC has been amended three times and codified in Directive 2011/92/EU. Under this directive, Member States must ensure that projects likely to have significant effects on the environment by virtue of their nature, size or location are made subject to an environmental impact assessment.

          - Article 6 of the Habitats Directive requires an appropriate assessment of any plan or project which, alone or in combination with other plans or projects, is likely to have a significant effect on a Natura 2000 site.

          - The Strategic Environmental Assessment Directive (2001/42/EC; Strategic Environmental Assessment, SEA) requires certain plans and programmes in the public sector to undergo a systematic environmental assessment. The SEA directive specifically defines biodiversity as an issue that must be included in the environmental report.

These provisions have been transposed into the Belgian federal and regional legal framework. However, it is necessary to help the initiators of relevant projects, plans and programmes assess whether their projects, plans and programmes are likely to have a significant impact on biodiversity and, if so, whether they should be subject to a SEA (e.g. by drafting guidelines or establishing an advisory committee with biodiversity experts). In addition, a set of biodiversity criteria to be considered as part of the environmental assessment, i.e. in the assessment report, may also prove useful in this regard.