The Evidence Gap: How Environmental Claims Standards in 2026 Diverge Across the US, EU, and UK

Every multinational making environmental claims now operates under at least three distinct evidentiary regimes, each with different thresholds for what counts as "substantiated," different enforcement mechanics, and different consequences for getting it wrong. The gap between data that is good enough for an internal sourcing decision and data that will survive regulatory scrutiny in a consumer-facing claim is widening in all three jurisdictions, but it is widening in different directions and at different speeds.

This divergence matters right now because the regulatory ground shifted meaningfully in 2025. In the US, the SEC abandoned its defense of federal climate disclosure rules while California pressed ahead with mandatory emissions reporting under SB 253. In the EU, the Commission paused the Green Claims Directive, only for the Empowering Consumers for the Green Transition Directive (ECGT) to march toward its September 2026 enforcement date. And in the UK, the Competition and Markets Authority gained the power to directly fine companies up to 10% of global turnover for misleading environmental claims without court proceedings. Companies that built their compliance strategies around a single framework are exposed.

The US: Fragmented Authority, Rising State-Level Pressure

The federal evidence standard for environmental marketing claims rests on the FTC's Green Guides, last substantively updated in 2012. The Guides require "competent and reliable scientific evidence," defined as tests, analyses, or research conducted by qualified persons using methods generally accepted in the relevant field, before a claim is made. But the Guides contain no guidance on carbon neutrality, net-zero claims, or Scope 3 emissions. The FTC solicited public comment in 2022 on whether to address climate claims, but as of early 2026, no updated Guides have been issued, and a revision appears unlikely under the current administration.

That federal vacuum is being filled by state action. California's SB 253, signed in October 2023, requires US-organized entities with revenues exceeding $1 billion doing business in California to publicly disclose Scope 1, 2, and eventually Scope 3 emissions per the GHG Protocol. The California Air Resources Board's proposed regulations, published December 2025, set an August 10, 2026 deadline for first Scope 1 and 2 reports, with limited assurance requirements starting in the 2027 cycle. Constitutional challenges remain live, with a Ninth Circuit injunction already granted for the companion SB 261 climate-risk statute, though SB 253 itself remains enforceable. Meanwhile, the SEC's climate disclosure rule, adopted March 2024, has never taken effect: the Commission ended its defense in March 2025, and the Eighth Circuit placed the case in abeyance in September 2025, telling the SEC to either defend or formally rescind the rule.

The operational consequence is a two-track evidence system within the US itself. For consumer-facing marketing, the FTC's deception standard applies but lacks climate-specific clarity. For disclosure, binding requirements are state-level and jurisdiction-specific. A company that treats its SB 253 emissions data as interchangeable with marketing claim substantiation is making a category error: disclosure data demonstrates what a company emits, while claims evidence must demonstrate that a specific environmental benefit is real, measurable, and not misleading in context.

The EU: Retreat on Process, Advance on Prohibitions

The EU's evidence landscape splits into two regulatory tracks moving at different speeds. The Green Claims Directive, which would have required mandatory scientific substantiation, lifecycle assessment, and ex-ante third-party verification of all explicit environmental claims, was paused in June 2025 after political resistance from the European People's Party over disproportionate burden on micro-enterprises. Its future remains uncertain.

But the ECGT, adopted February 2024 and requiring member state transposition by March 2026 with enforcement from September 2026, introduces specific prohibitions that function as de facto evidence standards. Generic claims like "eco-friendly" or "green" are banned unless accompanied by a clear specification on the same medium. Carbon neutrality claims based on offsetting require third-party verification. Sustainability labels must be backed by certified schemes. The December 2025 European Commission guidance confirmed B2B practices and CSRD reporting are generally out of scope, but a Spanish court decision in Iberdrola v. Repsol demonstrated the boundary is porous: corporate sustainability communications on investor-focused websites can still be assessed as consumer-facing if they influence brand perception.

The Omnibus I simplification package, provisionally agreed in December 2025 and formally adopted by the Council on 24 February 2026, further complicates the picture. It narrows the CSRD's scope to companies with more than 1,000 employees and EUR 450 million turnover, slashes mandatory ESRS data points from roughly 1,073 to 320, and permanently caps assurance at the limited level. The tension for multinationals: the ECGT creates enforcement liability around consumer claims from September 2026, while the system meant to define how to substantiate those claims is indefinitely on hold. Companies will need to build their own substantiation frameworks meeting the ECGT's prohibitions using defensible but not yet harmonized methodologies. "Defensible" here means evidence a regulator or court would accept as sufficient to demonstrate the claim is not misleading to an average consumer, considering lifecycle implications and material trade-offs.

For organizations evaluating whether their claims evidence architecture is fit for purpose across the EU, pressure-testing your substantiation methodology against both the ECGT prohibitions and the unfair commercial practices framework before September 2026 is a necessary step, not a discretionary one.

The UK: Operational Enforcement with Direct Financial Teeth

The UK stands apart by combining a principles-based standard with newly potent enforcement machinery. The CMA's Green Claims Code, in effect since September 2021, requires claims to be truthful, clear, not omit material information, make fair comparisons, consider the full lifecycle, and be substantiated. Since April 6, 2025, the DMCCA gives the CMA power to investigate, determine breaches, and impose fines of up to 10% of global turnover without court involvement.

This shift from court-dependent to direct administrative enforcement is the most consequential change in any of the three jurisdictions in 2025. The CMA has signaled a phased approach, targeting egregious breaches first, and its guidance explicitly recognizes environmentally motivated consumers as potentially vulnerable. A summer 2025 report by London Economics, reviewing nearly 10,000 products against the Code using AI-driven analysis, found widespread non-compliance across consumer goods. The CMA had already secured commitments from ASOS, Boohoo, and George at Asda and issued sector-specific fashion guidance in September 2024. For financial services, the FCA's anti-greenwashing rule, effective since May 2024, applies a higher "fair, clear, and not misleading" standard to all sustainability claims by authorized firms.

Where the Grey Areas Create Operational Risk

Three structural grey areas deserve particular attention. First, carbon offset and neutrality claims are diverging sharply: the EU's ECGT will require third-party verification for offset-based neutrality claims; the UK's CMA already treats them with heightened skepticism; the US has no specific federal guidance. A claim substantiated through verified offsets may satisfy one jurisdiction while failing another if consumers reasonably interpret "carbon neutral" as meaning zero emissions rather than a calculated offset balance.

Second, the boundary between B2B data sharing and B2C claims is less clean than compliance frameworks assume. The ECGT guidance excludes B2B practices, but the Iberdrola v. Repsol precedent shows corporate websites can be assessed as consumer-facing. The UK's Code applies to any claim aimed at UK consumers, including by non-UK businesses.

Third, limited assurance on emissions data under SB 253 or the CSRD provides a lower confidence threshold than most consumers would assume lies behind a "verified" claim. Decision-grade evidence for claims purposes, meaning evidence robust enough to withstand regulatory challenge, requires traceability to primary data, documented methodologies, explicit boundary definitions, consideration of trade-offs, and review against reasonable consumer interpretations.

A Cross-Jurisdictional Evidence Governance Framework

Companies need a unified evidence governance process that flexes to the highest applicable standard. At the first layer, separate evidence into two categories: disclosure evidence (feeding SB 253, CSRD, SEC filings) and claims evidence (supporting marketing copy, labels, corporate positioning). These draw from overlapping data but require different substantiation levels and approval authorities. They are not interchangeable.

At the second layer, every external claim should pass a four-part test: it must be specifically true (evidence supports the exact assertion, not a broader one); contextually complete (no material omissions that would change audience interpretation); jurisdictionally mapped (reviewed against each market's standard); and documented with an audit trail linking the published statement to source data.

At the third layer, assign clear governance ownership. Marketing teams should not self-certify claims. Legal review alone is insufficient without subject-matter data quality input. The most resilient model uses a cross-functional claims review committee spanning sustainability, legal, marketing, and internal audit, with authority to approve or block claims before publication and a standing mandate to revisit claims when underlying data changes.

If your organization is preparing for the ECGT's September 2026 enforcement date, building SB 253 reporting infrastructure, or navigating the CMA's new enforcement powers, Gasilov Group's cross-jurisdictional claims advisory practice audits evidence architectures, pressure-tests substantiation against the applicable standard in each market, and designs the internal governance structures that prevent claims risk before it reaches the regulator. Contact us to scope an engagement:

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Written by: Gasilov Group Editorial Team

Reviewed by: Seyfi Gasilov, Partner, Corporate Strategy & Regulatory Governance

Brings more than twenty years guiding organizations through strategic growth, governance challenges, and cross border compliance with a combined legal and operational lens.

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Frequently Asked Questions (FAQ):

What is the difference between evidence required for sustainability disclosures and evidence needed for environmental marketing claims?

Disclosure evidence, such as emissions data reported under California's SB 253 or the EU's CSRD, demonstrates what a company emits, what risks it faces, and what targets it has set. Claims evidence must go further: it must prove that a specific environmental benefit statement is true, contextually complete, and not misleading to its audience. A company can fully comply with emissions disclosure while making a marketing claim that regulators consider misleading because it omits material context or overstates a benefit. These two categories draw from overlapping data but require different substantiation standards and approval authorities. They should never be treated as interchangeable.

How does the UK CMA enforce greenwashing claims differently after the DMCCA took effect in April 2025?

Since April 6, 2025, the CMA can directly investigate, determine non-compliance, and impose fines of up to 10% of global turnover for misleading environmental claims without going through court. This replaced a court-dependent model that limited enforcement pace and volume. By comparison, the EU's Green Claims Directive, which would have introduced harmonized enforcement with penalties of up to 4% of turnover, was paused in June 2025. The US relies on FTC case-by-case enforcement. The UK regime is currently the most enforcement-ready of the three for consumer-facing environmental claims.

What evidence standard does the FTC require for carbon neutrality or net-zero claims?

The FTC's Green Guides, last updated in 2012, do not specifically address carbon neutrality, net-zero, or climate-related claims. The general standard requires "competent and reliable scientific evidence" from qualified persons using accepted methodologies. For carbon neutrality, a company would need evidence demonstrating its emissions calculation methodology, the quality and additionality of offsets used, and that the overall claim would not mislead a reasonable consumer. The FTC solicited comment in 2022 on adding climate guidance, but no update has been published.

Will the EU still enforce greenwashing rules now that the Green Claims Directive has been paused?

Yes. The ECGT, adopted February 2024, is unaffected and requires member state enforcement from September 2026. It prohibits generic environmental claims without clear specification, requires third-party verification for carbon neutrality and forward-looking claims, and mandates certified schemes for sustainability labels. Member states' existing national advertising and consumer protection laws also remain in force. Companies marketing to EU consumers should prepare regardless of the Green Claims Directive's future.

How should multinational companies structure internal governance to manage environmental claims evidence across all three jurisdictions?

The most effective approach separates disclosure evidence from claims evidence at the data architecture level, then routes every external claim through a cross-functional review testing it against the highest applicable standard in each market. This typically involves a claims review committee spanning sustainability, legal, marketing, and internal audit, with authority to approve or block claims before publication. Each claim should carry a four-part substantiation file: factual basis, contextual completeness assessment, jurisdictional mapping, and audit trail linking the statement to underlying data. Post-publication monitoring is also necessary, because changes in data can retroactively render a previously compliant claim misleading.