1. Introduction

A green taxonomy is a legally or institutionally recognised classification system that identifies which economic activities, projects or investments can legitimately be regarded as environmentally sustainable. Its principal purpose is to create a common language for sustainable finance, reduce greenwashing, improve comparability between financial products and direct capital toward activities that contribute to environmental objectives.

The European Union Taxonomy is the most developed example. Regulation (EU) 2020/852 establishes a unified classification system for determining whether an economic activity is environmentally sustainable. The framework is particularly important because it connects environmental criteria with investment disclosure and financial-market regulation. (curia)

For energy law, taxonomy is increasingly significant because investments in renewable electricity, electricity networks, storage, hydrogen, energy efficiency and other transition technologies can be classified according to legally specified environmental criteria.

2. Meaning of Green Taxonomy

A green taxonomy generally performs four functions:

Classification – identifies environmentally sustainable economic activities.

Standardisation – establishes common technical criteria.

Disclosure – requires investors or companies to communicate the environmental characteristics of investments.

Capital allocation – facilitates investment in activities considered environmentally sustainable.

The EU Taxonomy Regulation expressly establishes a framework for determining when an economic activity qualifies as environmentally sustainable for purposes of establishing the degree to which an investment is environmentally sustainable. (curia)

Thus, taxonomy does not simply label an entire company as "green." It generally operates at the level of economic activities.

For example, a company may conduct both:

renewable-energy generation; and

fossil-fuel-related activities.

The taxonomy can therefore distinguish between individual activities rather than treating the entire company as environmentally sustainable.

3. The Six Environmental Objectives

Article 9 of the EU Taxonomy Regulation identifies six environmental objectives:

1. Climate-change mitigation

Activities must contribute substantially to reducing greenhouse-gas emissions or otherwise support the transition toward a low-carbon economy.

Examples include:

renewable electricity generation;

certain electricity-storage activities;

energy-efficiency improvements;

low-carbon technologies.

2. Climate-change adaptation

Activities may qualify where they substantially reduce material physical climate risks or support adaptation to climate change.

Examples can include:

climate-resilient infrastructure;

flood-resistant infrastructure;

adaptation technologies.

3. Sustainable use and protection of water and marine resources

This objective addresses sustainable water use, water quality and protection of aquatic ecosystems.

4. Transition to a circular economy

The objective focuses on:

resource efficiency;

recycling;

reuse;

waste prevention;

longer product lifecycles.

5. Pollution prevention and control

Activities must contribute to preventing or reducing pollution of:

air;

water;

soil.

6. Protection and restoration of biodiversity and ecosystems

This concerns conservation and restoration of ecosystems and biodiversity.

These six objectives are expressly recognised in the Taxonomy Regulation and were confirmed by the General Court in ClientEarth v Commission, T-579/22. (curia)

4. Taxonomy Eligibility and Taxonomy Alignment

One of the most important distinctions in sustainable-investment law is between taxonomy eligibility and taxonomy alignment.

Taxonomy-eligible activity

An activity is eligible when it falls within an economic activity for which taxonomy criteria have been established.

Eligibility therefore asks:

"Is this type of economic activity covered by the taxonomy?"

Taxonomy-aligned activity

Alignment requires the activity to actually satisfy the applicable legal requirements.

Under Article 3 of the EU Taxonomy Regulation, an economic activity is environmentally sustainable where it:

makes a substantial contribution to one or more environmental objectives;

does not significantly harm the other environmental objectives;

complies with minimum safeguards; and

satisfies the applicable technical screening criteria. (curia)

Consequently:

Eligibility ≠ sustainability.

An activity can be taxonomy-eligible without being taxonomy-aligned.

This distinction is particularly important for investment funds and corporate disclosures because merely describing an activity as "taxonomy eligible" does not establish that the activity is environmentally sustainable.

5. Substantial Contribution Principle

The first substantive requirement is substantial contribution.

An economic activity must make a meaningful contribution to at least one environmental objective.

For example, an electricity-generation project could potentially qualify through substantial contribution to climate-change mitigation if it satisfies the applicable technical criteria.

The law therefore moves away from vague claims such as:

"This project is environmentally friendly."

Instead, classification is based on measurable legal and technical criteria.

This improves the objectivity of sustainable-investment classification.

6. Do No Significant Harm Principle

The Do No Significant Harm (DNSH) principle is central to green taxonomy.

A project cannot normally qualify merely because it benefits one environmental objective while seriously damaging another.

For example:

A project that substantially contributes to climate mitigation but causes significant environmental damage elsewhere may fail the taxonomy requirements.

DNSH therefore introduces a cross-environmental assessment.

It prevents the simplistic argument that an activity is sustainable merely because it reduces carbon emissions.

The Court's jurisprudence concerning the Taxonomy Regulation confirms that technical screening criteria must address whether activities cause significant harm to other environmental objectives. (curia)

7. Minimum Safeguards

Environmental sustainability is not assessed in isolation from fundamental social and governance standards.

The taxonomy framework also requires compliance with minimum safeguards.

These are designed to ensure that an activity classified as environmentally sustainable is not simultaneously associated with serious violations of fundamental standards concerning areas such as:

human rights;

labour rights;

responsible business conduct.

Thus, taxonomy combines environmental performance with minimum social-governance requirements.

8. Technical Screening Criteria

Technical screening criteria are the operational heart of taxonomy regulation.

They specify how regulators determine whether an activity actually meets the legal requirements.

Such criteria can involve:

emission thresholds;

energy-efficiency levels;

lifecycle considerations;

resource-use requirements;

pollution thresholds;

technological standards.

The General Court has emphasised that technical screening criteria must comply with the requirements of Article 19 of the Taxonomy Regulation, including consideration of scientific evidence and the precautionary principle. (curia)

This demonstrates that taxonomy is not merely a policy classification. It involves legally reviewable regulatory standards.

9. Sustainable Investment Classification

Green taxonomy should be distinguished from the broader concept of sustainable investment.

The EU sustainable-finance framework contains several interconnected but distinct regimes:

The European Commission has specifically recognised the interaction between the Taxonomy Regulation and the Sustainable Finance Disclosure Regulation (SFDR). (EUR-Lex)

This distinction is important because an investment can be described as sustainable under one regulatory framework without necessarily being identical in legal meaning to "taxonomy-aligned."

10. Taxonomy and Greenwashing

One of the primary reasons for introducing taxonomies is to combat greenwashing.

Greenwashing occurs when financial products, companies or projects are presented as environmentally sustainable without adequate evidence supporting the claim.

Taxonomy reduces this problem by replacing broad marketing descriptions with:

defined categories;

technical criteria;

disclosure obligations;

third-party verification in relevant contexts;

regulatory supervision.

This is particularly important in the green-bond market.

SEBI has itself identified concerns about greenwashing and the importance of accepted standards and taxonomies for investor confidence in India's green-bond market. (Securities and Exchange Board of India)

11. Indian Legal and Regulatory Context

India does not simply replicate the EU Taxonomy model. Instead, its sustainable-finance framework has developed through several regulatory and policy instruments.

SEBI has established regulatory requirements for green debt securities and has progressively expanded the Indian ESG debt framework.

As of 2025, SEBI's framework covered:

green debt securities;

social bonds;

sustainability bonds; and

sustainability-linked bonds.

SEBI has also required independent third-party reviewers/certifiers for relevant ESG debt securities. (Securities and Exchange Board of India)

This is significant because sustainable investment classification increasingly depends on verification rather than issuer claims alone.

India's regulatory development can therefore be understood as a movement from broad green-finance principles toward increasingly formalised classification and disclosure requirements.

12. Green Taxonomy and Electricity Markets

Taxonomy has major implications for electricity-sector investment.

Potentially relevant categories include:

Renewable generation

Investment in:

solar;

wind;

geothermal;

certain hydropower projects;

other qualifying renewable technologies.

Electricity networks

Grid infrastructure may be relevant where it supports environmental objectives and satisfies applicable technical criteria.

Energy storage

Battery storage and other storage technologies can support:

renewable integration;

grid flexibility;

reduction of curtailment;

system decarbonisation.

Energy efficiency

Investment in energy-efficient infrastructure can potentially qualify where the applicable criteria are met.

Hydrogen

Renewable or low-carbon hydrogen projects may become important areas of taxonomy classification.

Therefore, taxonomy can influence not only financial markets but also energy infrastructure planning and electricity regulation.

13. Important Case Law

A. ClientEarth v European Commission — T-579/22

Judgment: 10 September 2025.

This is one of the most directly relevant recent cases concerning the EU Taxonomy.

ClientEarth challenged the Commission's treatment of several activities under the taxonomy framework, including:

forest biomass;

bioenergy;

organic base chemicals;

plastics.

The applicants argued, among other things, that the technical screening criteria failed to satisfy the requirements of the Taxonomy Regulation.

The General Court dismissed the action. It examined the requirements applicable to technical screening criteria, including:

scientific evidence;

precautionary principles;

substantial contribution;

DNSH;

the regulatory discretion involved in establishing technical criteria. (curia)

Legal significance

The case demonstrates that taxonomy criteria are subject to judicial review.

It also establishes an important principle:

Technical taxonomy criteria must be scientifically and legally grounded, but the Commission retains regulatory discretion when balancing environmental, scientific, economic and feasibility considerations.

B. Robin Wood and Others v Commission — T-575/22

The General Court also addressed challenges concerning taxonomy treatment of forest management and forest biomass.

The case concerned whether activities involving forest biomass satisfied the requirements of the Taxonomy Regulation, including substantial contribution and DNSH requirements. The General Court delivered judgment on 18 March 2026. (Infocuria)

Legal significance

The litigation illustrates a fundamental problem in taxonomy law:

Whether an activity that may contribute to decarbonisation can nevertheless cause environmental harm elsewhere.

This is exactly the regulatory problem addressed by the DNSH principle.

C. Fédération environnement durable and Others v Commission — T-583/22

The General Court considered challenges concerning taxonomy treatment of wind-power electricity generation.

The case examined technical screening criteria and, among other matters, whether the taxonomy framework could legitimately establish particular criteria concerning environmental objectives such as circular economy. (EUR-Lex)

An appeal was subsequently brought before the Court of Justice in C-764/25 P, illustrating that taxonomy classification remains an evolving area of EU environmental and financial law. (juris.curia.europa.eu)

Legal significance

The case demonstrates that even apparently "green" technologies can generate legal disputes over:

lifecycle impacts;

material use;

recycling;

environmental thresholds;

scientific methodology.

D. Dassault Aviation v Commission — T-77/24

A particularly important recent development is the General Court's 24 June 2026 judgment concerning aircraft manufacturing.

The Court held that the Commission had made a manifest error of assessment in excluding the manufacture of aircraft intended for private or commercial business aviation from certain transitional activities under the taxonomy framework, and annulled the relevant exclusion. (curia)

Legal significance

This case demonstrates that:

taxonomy classification has real legal and financial consequences;

classification decisions can affect companies' access to sustainable-finance markets;

the Commission's technical classification decisions remain subject to judicial review.

It also confirms that taxonomy status is not merely a voluntary marketing label.

14. Taxonomy as a Form of Financial Regulation

Green taxonomy represents an important shift in the relationship between environmental law and financial law.

Traditional environmental regulation generally focused on:

pollution permits;

environmental impact assessments;

emission standards;

resource management.

Taxonomy adds another regulatory mechanism:

classification of economic activity for purposes of capital allocation and financial disclosure.

Consequently, environmental law increasingly influences:

investment funds;

banks;

institutional investors;

bond markets;

corporate reporting;

securities regulation.

This makes sustainable finance an important component of modern energy law.

15. Legal Challenges

Green-taxonomy regimes face several legal challenges.

1. Scientific uncertainty

Environmental science changes rapidly. Technical criteria can become outdated as technology develops.

2. Regulatory discretion

Governments and regulators must decide where thresholds should be established.

3. Technology neutrality

Regulation must avoid unnecessarily favouring one technology where several technologies can achieve comparable environmental objectives.

4. Greenwashing

Weak criteria can allow environmentally questionable projects to receive green classifications.

5. International fragmentation

The EU, India, China and other jurisdictions may adopt different classification systems.

This can increase compliance costs for multinational investors.

6. Transition activities

One of the most difficult questions concerns activities that are not currently zero-carbon but may contribute to decarbonisation during the transition.

The EU Taxonomy expressly recognises the concept of transitional activities, creating legal debates about which technologies should qualify.

16. Importance for Energy Law

Green taxonomy is becoming an important bridge between energy policy, environmental regulation and financial regulation.

For an electricity project, legal sustainability may increasingly involve three separate questions:

First: Is the activity legally permissible?

Second: Does it satisfy environmental standards?

Third: Does it qualify under a recognised sustainable-finance taxonomy?

These questions are not identical.

A legally permitted electricity project does not automatically become a taxonomy-aligned investment.

This distinction is critical for:

renewable-energy developers;

electricity utilities;

banks;

infrastructure funds;

institutional investors;

green-bond issuers;

regulators.

17. Conclusion

Green taxonomy and sustainable investment classification transform sustainability from a broad policy aspiration into a structured legal classification system.

The central principles are:

classification of economic activities;

substantial contribution to environmental objectives;

Do No Significant Harm;

minimum safeguards;

technical screening criteria;

transparent disclosure;

scientific and regulatory accountability.

The EU Taxonomy provides the most developed legal model, while India's framework has progressively strengthened green and ESG debt regulation through SEBI. SEBI's current framework includes green, social, sustainability and sustainability-linked debt securities and incorporates independent third-party review mechanisms. (Securities and Exchange Board of India)

Recent EU cases such as ClientEarth, Robin Wood, Fédération environnement durable, and Dassault Aviation demonstrate that taxonomy classification is not merely an administrative or financial exercise: it raises substantive questions of environmental science, regulatory discretion, investor protection, corporate disclosure and judicial review. (curia)

In energy law, the long-term significance of taxonomy lies in its ability to connect environmental performance with the allocation of private capital. As sustainable-finance regulation develops, the question of whether an electricity, hydrogen, storage or infrastructure activity satisfies a recognised taxonomy can become almost as important for investment decisions as traditional questions of licensing and economic regulation.