81% of ASA greenwashing rulings could have been avoided with ESG assurance, Menzies analysis finds
London, 26 June 2025 – Almost 2 in 3 greenwashing-related advertising complaints upheld by the UK’s Advertising Standards Authority (ASA) could have been avoided if the claims had undergone independent ESG assurance during the campaign development process, according to new analysis from advisory firm Menzies LLP. With ESG assurance, external experts verify that environmental claims are accurate, evidenced, and clearly worded.
Regulators are tightening their grip on environmental messaging – April’s Digital Markets, Competition and Consumers Act now gives the CMA power to fine brands up to 10% of global turnover for misleading green claims, without court proceedings. Against this backdrop, the findings highlight a major blind spot for many brands and the agencies that advise them.
The analysis, published in Menzies’ new Green Claims, Red Flags report, reviewed 1,090 ASA rulings issued between March 2020 and March 2025. Of the 53 relating to greenwashing, Menzies’ ESG assurance team found that:
- 62% would have avoided breaching ASA rules entirely with proper evidence and framing
- A further 19% could have been at least partly avoided with ESG assurance
Richard Singleton, Sustainability Director at Menzies, comments: “There’s a real distinction between getting it right and just hoping you’re not challenged. ESG assurance helps with both. In many of these cases, claims could have been avoided entirely with clearer language or stronger evidence. But even where that wasn’t possible, assurance would have flagged the risks, allowing brands and agencies to rethink the message before it went public.”
The most common failings included bold claims like “100% carbon neutral” with no clear evidence, statements that ignored the full life cycle of a product or service, and vague terms like “eco-friendly” or “sustainably sourced” with no agreed definitions.
The report also reveals which sectors are most exposed. Retail, FMCG and travel brands topped the list of ASA rulings, with energy, automotive and financial services not far behind — industries where bold environmental messaging is common, but often not backed by sufficient proof.
Richard Singleton comments: “An ASA ruling isn’t just a bad headline or a career-limiting move for a CMO or agency lead. It can cause real reputational damage for a brand, say nothing of the cost of pulling campaigns and reworking messaging. And given the fines brands are potentially liable for due to the Digital Markets, Competition and Consumers Act, they quite literally can’t afford to be negligent on this.
Most of the brands we analysed weren’t trying to mislead — but without independent checks, it’s easy to get it wrong. With so much grey area in environmental messaging, you need people who can challenge claims, test assumptions, and back it all with evidence.
ESG assurance doesn’t need to slow anything down. Done early in the process — at the concept or planning stage — it can be quick, focused and hugely valuable. It’s not just about risk mitigation, either. A good assurance review can help uncover stronger claims and improve how brands communicate sustainability, not just in their marketing, but across wider corporate reporting.”
Green Claims, Red Flags offers a practical framework for marketing, ESG, legal and creative teams developing sustainability communications. It includes:
- The ASA rules most commonly breached in green ads
- The industries with the highest number of greenwashing bans
- Real-world examples of where ESG assurance could have prevented ad bans
- A step-by-step guide to integrating ESG assurance into campaign development
- Tips to prepare ESG data for audit
- A pre-launch checklist for reviewing sustainability claims
More on Menzies’ ESG assurance services
Download our ESG Assurance Research Report here
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