Recent rulings by the UK’s Advertising Standards Authority (ASA) highlight the risks companies face when making vague or unsubstantiated environmental claims in their advertising.

In December, the ASA banned ads from Nike, Superdry, and Lacoste for using terms like “sustainable” or “sustainable materials” without explaining or substantiating these claims.

ASA rulings

The ASA objected to the following advertising phrases:

  • Nike: “Nike Tennis Polo Shirts – Serve An Ace With Nike […] Sustainable Materials”
  • Superdry: “Sustainable style. Unlock a wardrobe that combines style and sustainability”
  • Lacoste: “Lacoste Kids – Sustainable […] clothing”

The ASA found these statements to be misleading because none of the ads clarified what was meant by “sustainable”, nor did they provide sufficient evidence to substantiate the claims.

Relevant CAP Code rules

The Committee of Advertising Practice (CAP) Code sets out rules for advertising in the UK. The ASA found that each advertisement breached the following sections:

Misleading Advertising

  • 3.1 Marketing communications must not materially mislead or be likely to do so.

Substantiation

  • 3.7 Before distributing or submitting a marketing communication for publication, marketers must hold documentary evidence to prove claims that consumers are likely to regard as objective and that are capable of objective substantiation. The ASA may regard claims as misleading in the absence of adequate substantiation.

Environmental Claims

  • 11.1 The basis of environmental claims must be clear. Unqualified claims could mislead if they omit material information.
  • 11.2 The meaning of all terms used in marketing communications must be clear to consumers.
  • 11.3 Absolute claims must be supported by a high level of substantiation. Comparative claims such as “greener” or “friendlier” can be justified, for example, if the advertised product provides a total environmental benefit over that of the marketer’s previous product or competitor products and the basis of the comparison is clear.
  • 11.4 Marketers must base environmental claims on the full life cycle of the advertised product, unless the marketing communication states otherwise, and must make clear the limits of the life cycle. If a general claim cannot be justified, a more limited claim about specific aspects of a product might be justifiable. Marketers must ensure claims that are based on only part of the advertised product’s life cycle do not mislead consumers about the product’s total environmental impact.

In summary, the CAP Code requires that environmental claims in advertising must be clear, specific, and backed by robust evidence. Vague or absolute terms such as “sustainable” are likely to mislead consumers and fall short of advertising standards.

Brand responses

Each brand submitted a response to the ASA seeking to substantiate their advertisement’s sustainability claims:

  • Nike stated that “sustainable materials” referred to products containing recycled materials, with more detailed information available on its website. It highlighted character limitations in Google ads and noted that only products meeting certain recycled content thresholds could display the “sustainable materials” banner. It used a third-party tool to assess the environmental impact of materials in order to support environmental claims about its products. Nike noted that the ad had not run since June 2025, in line with its standard advertising practices.
  • Superdry stated that its ad aimed to highlight products with sustainability attributes and certifications, not to suggest all products were sustainable. It noted that substantiation and certification details were available on its website, and confirmed the ad had been withdrawn and would not be used again.
  • Lacoste stated that its claim reflected efforts to improve the sustainability of its Kids range, supported by increased use of certified fabrics and life-cycle analysis showing reduced environmental impact. It acknowledged the difficulty of substantiating terms like “sustainable” and confirmed the ad was removed and would not be repeated in that form.

The ASA upheld its ruling in all cases and instructed each company “to ensure that the basis of future environmental claims, and their meaning, was made clear and that a high level of substantiation was held in support”.

These decisions are part of a wider ASA crackdown on ambiguous environmental claims. Earlier this year, the ASA also banned a Red Tractor ad for failing to substantiate claims that its products were “Farmed with Care” and met “Certified Standards”.

Takeaway

These rulings send a clear message to brands: it is not enough simply to promote products as ‘green’, ‘eco-friendly’, or ‘sustainable’. Brands must take care that environmental messaging is clear and specific, and they must be ready to support such claims with robust evidence if it is sought by the ASA in order to meet the CAP Code requirements.

For further discussion or advice on compliance, please contact James Tumbridge, Robert Peake, and Anne-Marie Harding.