Implications of ICJ’s Climate Change Opinion on Corporate Sustainability Due Diligence

On 23 July 2025, the International Court of Justice (ICJ) issued an Advisory Opinion on Climate Change, which unequivocally affirmed that:

1. Access to a clean, healthy, and sustainable environment is a human right.
2. This right is a prerequisite for the enjoyment of all other human rights, including:
   1. the right to life,the right to health, and
   1. the right to an adequate standard of living.
3. Climate change poses a direct and severe threat to these human rights, and efforts to address climate change must be grounded in respect for human rights.

This is a historic legal moment.

The ICJ has not only recognized environmental protection as a human right, echoing the UN Human Rights Council’s 2022 resolution, but it also clarified that States have a legal responsibility to regulate the activities of private actors, including companies, as part of their duty of due diligence under international law.

In doing so, the ICJ places human rights due diligence at the heart of climate action, and confirms that climate justice and human rights are inseparable.

What is an ICJ Advisory Opinion?

The International Court of Justice is the world’s highest court. Its advisory opinions are issued at the request of UN organs or specialized agencies to provide legal clarification on complex questions. This particular opinion on climate change was issued at the request of States through the UN General Assembly.

Although advisory opinions are not legally binding, they carry significant weight and authority in international law. They are frequently cited by courts, UN agencies, and governments, and over time, they can contribute to the formation of customary international law, which is binding.

Governments often rely on advisory opinions to justify domestic legislation or their international positions.

What Does the ICJ Opinion Say About States’ Legal Obligations? 

The ICJ makes several important points:

1. States have a legal obligation under international law to protect the climate system and to guarantee the effective enjoyment of human rights.
2. Measures taken by States to fulfill this obligation may include adopting standards and legislation and regulating private sector activities within their jurisdictions.
3. Failure to take appropriate action on climate change, including failure to regulate corporate activities, may constitute an internationally wrongful act.

In paragraph 428 of the advisory opinion, the ICJ explicitly states:

“A State may be responsible where, for example, it has failed to exercise due diligence by not taking the necessary regulatory and legislative measures to limit the quantity of emissions caused by private actors under its jurisdiction.”

In paragraph 403, the ICJ opinion lists regulating private activities that harm the environment as an appropriate measure that States can take to fulfill their legal obligation under international law:

“In order to guarantee the effective enjoyment of human rights, States must take measures to protect the climate system and other parts of the environment. These measures may include, inter alia, taking mitigation and adaptation measures, with due account given to the protection of human rights, the adoption of standards and legislation, and the regulation of the activities of private actors. Under international human rights law, States are required to take necessary measures in this regard.”

With this explicit warning from the world’s highest court – that States may be held internationally responsible for failing to regulate corporate behavior – it is likely that more governments will introduce or accelerate mandatory sustainability legislation.

What Does The ICJ Opinion Mean for Corporate Sustainability Legislation?

This advisory opinion adds strong legal backing to efforts pushing for mandatory corporate sustainability legislation. It directly strengthens the case for laws such as the EU Corporate Sustainability Due Diligence Directive (CSDDD), especially at a time when political opposition is seeking to weaken and delay their implementation.

This ICJ advisory opinion is likely to influence how governments justify legislative action and encourage more States to regulate corporate sustainability activities, if they have not done so already. At the EU level, it may also influence the current positions of some EU member states on the omnibus proposal, which was introduced by the EU Commission in February 2025 with the aim to amend key requirements of the EU CSDDD and the Corporate Sustainability Reporting Directive (CSRD), among other regulations.

For the latest on the omnibus proposal, read this CORE Message: Reflections on the Omnibus Process and EU Council’s Negotiating Position

What are the Implications of the ICJ Opinion for Corporate Sustainability Due Diligence?

This ICJ advisory opinion provides a foundational legal reference that will guide corporate sustainability practices. In countries with corporate sustainability laws, it reinforces the legal basis for holding companies accountable for environmental and human rights harms.

Companies that fail to mitigate their environmental and human rights impacts may trigger legal consequences not only for themselves, but for the States in which they operate, particularly where States fail to take appropriate measures to protect the climate and guarantee the enjoyment of human rights.

By sending a clear message that companies must act to prevent climate harms and protect the right to a clean, healthy and sustainable environment, the opinion also empowers civil society and affected communities to advocate for greater business accountability.

To ensure that their operations do not adversely impact environmental and human rights, companies must conduct due diligence, that is, identify, assess and address the environmental and human rights impacts of their activities and value chains.

As such, the ICJ advisory opinion serves as a wake-up call for States to take appropriate action on climate change and a powerful incentive for companies to strengthen their corporate sustainability due diligence processes – if they have not done so already.

Serra for the CORE team