This horizontal integration clause is a cornerstone of EU sustainability law. It imposes an obligation to mainstream environmental considerations across all EU policy areas, from agriculture and energy to transport and competition. Case law of the CJEU (e.g. Commission v Germany, C-301/95) has interpreted Article 11 (and its predecessors) as requiring that environmental concerns be balanced and weighed alongside other objectives in policy design and implementation.1 It emphasised the duty to integrate environmental considerations into state aid assessments. Article 11 TFEU mirrors the cross-cutting logic of SDG 13 (Climate Action) and SDG 9 (Industry, Innovation and Infrastructure).

Despite the horizontal integration clause, environmental objectives are frequently subordinated to the imperatives of economic growth and market integration. The internal market logic often trumps environmental considerations, as seen in the CJEU’s proportionality analysis. Environmental goals are treated as balancing factors, not foundational constraints. The application of proportionality, especially in internal market cases, frequently tilts in favour of economic freedoms, reducing the transformative potential of Article 11.

Article 119, however, already includes an additional economic dimension: such activities by the Member States and the Union are subject to the following guiding principles: stable prices, sound public finances and monetary conditions, and a sustainable balance of payments; later, Article 140 refers to the sustainability of the public finances.2 The 13th Protocol on the convergence criteria states that the price stability criterion means that a Member State has achieved sustainable price stability and an inflation rate that is no more than 1½ percentage points above the average inflation rate of the three best-performing Member States in terms of price stability over a period of one year preceding the examination.3

The TFEU creates the legal frameworks for harmonisation and subsidiarity of environmental policy (Articles 191–193), while still privileging diversity in National ecological standards within an otherwise EU-wide coherence.

This article describes the main objectives of EU environmental policy that include: (i) preservation, protection and improvement of environmental quality; (ii) protection of human health; (iii) prudent and rational use of natural resources; (iv) promoting measures to combat climate change at an international level. Article 191 also incorporates the precautionary, prevention, rectification-at-source, and ‘polluter pays’ principles, which provide legal backing for a series of EU environmental legislation. It describes that environmental policy will, at a minimum, be based upon high levels of protection while acknowledging regional diversity and enhancing international cooperation — legitimising (potentially) the EU’s role in global climate and sustainability governance (e.g. Paris Agreement, SDGs). In Janecek v Freistaat Bayern (C-237/07) the ECJ held that individuals have standing to demand action when air quality standards are violated, in this way giving effect to the objectives outlined in Article 191 TFEU.4 It supports SDG 3 (Good Health and Well-being) and SDG 15 (Life on Land), especially via pollution prevention and protecting ecosystems.

Article 192 provides the EU with a legal basis to adopt legislation in environmental matters through the ordinary legislative procedure, and special procedures on taxation, planning, land use, and energy. Article 193 provides a Member State with the ability to take measures which are stricter in nature than the EU minimum harmonisation rules in environmental law. Decisions on Package Waste Article 193 of the TFEU were made in Commission v Germany (C-141/02),5 where Germany adopted regulations on packaging waste. The Court allowed the Member States, subject to the EU principles on proportionality and non-discrimination, to have stricter regulations. The environmental competences Articles 191-193 are fragmented and sectoral, and they lack a systemic legal framework that could potentially streamline climate, biodiversity, energy, and social justice under the one concept of sustainability. The absence of a climate article in the TFEU at a time of existential climate crisis reflects this limitation. Compared to constitutional innovations in national systems e.g. Germany’s Article 20a or the 2022 constitutional amendment in Italy, the TFEU seems doctrinally conservative and slow to respond.

Amendments should be made to the TFEU to include a specific article on climate, one that would establish climate neutrality and resilience as constitutional principles. Third, the EU should introduce a Sustainability Compliance Mechanism to guarantee the full realisation of Article 11 in all policy areas. Fourth, creating an intergenerational stewardship body - such as a European Commissioner or Ombudsperson for Future Generations - could guarantee continuity of systematic guardianship over long-term sustainability objectives.