Some sectors are rarely out of the greenwashing spotlight, and that’s certainly the case with the fashion industry.

Having been the subject of various media probes into labour practices, marketing ploys and the sustainability implications of fast fashion in the past, the clothing retail sector has recently been under growing pressure over the positive claims that it makes around products.

Now the Competition and Markets Authority (CMA) has issued sector-specific guidance on how to avoid breaching greenwashing rules, including sending letters to 17 well-known but thus-far unnamed fashion brands pointing out what they need to do to ensure they toe the line.

It’s certainly a shot across the bows by the regulator into practices that it sees as breaching the rules, and follows a CMA deal with Asos, Boohoo and Asda clothing brand George earlier this year in which all three companies undertook to make changes to their green claims to avoid further regulatory scrutiny.

The full compliance guide can be read here. To save you the effort though, here’s a summary.

Firstly, as well as ensuring that all claims are fair and accurate, there’s a requirement to be transparent too - in other words, not to deliberately hide anything.

Secondly, brands must present targets or aims clearly and accurately.

The other stipulations are pretty obvious, but are designed to leave companies in zero doubt. They must not use images and icons in a misleading way, make sure that what they claim applies across an entire product range, provide further details about affiliations and associations, and - crucially - not mislead consumers with the brand or range name.

But the guidance also pulls no punches on any wider attempts to make a product appear to be more sustainable than it is, or on the consequences of transgression: “Broader, general or absolute claims - like ‘green’, ‘sustainable’ or ‘eco-friendly’ - are much more likely to be inaccurate and to mislead consumers. The meaning of words like these is unclear. Consumers are likely to assume that the product as a whole has a positive environmental impact, or at least no adverse impact. Unless you can prove that is the case, you risk falling short of your legal obligations.”

Penalties for infringement are set to be stiff - up to 10 per cent of global revenue, providing a key piece of legislation comes into force next year.

Last month, a report by a non-profit claimed that just a handful of fashion brands had published emissions reduction targets, and outlined that the UK’s clothing sector was particularly off the pace in becoming more sustainable.

Meanwhile, the EU’s Green Claims Directive maintains the principle of ex-ante verification by third-party experts when it comes to green claims in fashion marketing. In other words, you’ve got to back your claims up.

According to this piece in City AM, marketing and communications teams in the sector will largely welcome the CMA’s latest move to improve the clarity around where lines can be drawn.

But equally, the new guidance still brings with it a need for a rethink over how products are described, and the risk of a whole host of reputation issues for anyone that falls foul of the regulator.