Advertising Standards (ASA/CAP)

The ProCopywriters Code of Practice requires that we “comply with all relevant advertising codes and regulations” and “ensure claims are truthful, accurate and can be substantiated.”

In the UK, most advertising is regulated by the Advertising Standards Authority (ASA) under the CAP Code (for non-broadcast) and BCAP Code (for broadcast). Understanding these rules is essential for any copywriter working on marketing content.

The CAP Code applies to:

• Advertisements in newspapers, magazines and other print media
• Posters and billboards
• Direct mail and emails
• Online display ads and paid search
• Social media ads (paid content)
• Advertiser’s own marketing on their website
• Sales promotions and competitions

What it doesn’t cover:

• Editorial content (genuine journalism, not paid-for)
• Private correspondence
• Packaging* (covered by Trading Standards instead)
• Political advertising (covered by the Electoral Commission)

*Packaging can fall under the CAP Code if it is promotional in nature (e.g. on-pack promotions).

The CAP Code is built on four fundamental principles. All ads must be:

Legal

Ads must comply with the law. This seems obvious, but it means staying current with regulations in specific sectors and understanding what claims require particular evidence or disclaimers.

Decent

Ads shouldn’t contain anything likely to cause serious or widespread offence, taking account of the audience, medium, product and context.

Honest

Ads must not mislead by inaccuracy, ambiguity, exaggeration, omission or otherwise. This is where most complaints arise, and where copywriters need to be most careful.

Truthful

Objective claims must be supported by evidence. Subjective claims (matters of opinion) have more leeway, but the overall impression must still be accurate.

If you make an objective claim, you need evidence to back it up. This is called “substantiation.”

What counts as an objective claim:

• “Clinically proven” — needs clinical trial data
• “UK’s favourite” — needs market share or survey data
• “Saves you £200 a year” — needs calculation methodology
• “9 out of 10 recommend” — needs properly conducted survey

Substantiation should be:

• Relevant — directly supporting the claim made
• Robust — methodologically sound
• Recent — current at time of advertising
• Available — you should have it before making the claim

These are the areas where copywriters most often run into ASA trouble:

Misleading omissions

Leaving out important information that would affect consumer decisions. “From £9.99” requires the £9.99 option to be genuinely available, not just theoretical.

Exaggerated claims

Puffery is allowed (“probably the best lager in the world”) but claims that could be taken literally must be true.

Small print abuse

Important qualifications must be prominent. Burying key limitations in tiny footnotes doesn’t comply.

Testimonials and endorsements

Must be genuine, held before use, and representative of typical results. “Results not typical” doesn’t fix misleading headline claims.

Comparative advertising

You can compare with competitors, but comparisons must be like-for-like, verifiable, and not denigrating.

Some sectors have additional requirements in the CAP Code:

• Health and beauty — medical claims need robust evidence; cosmetic claims must reflect what products actually do
• Food and drink — health claims must be authorised; rules on HFSS products
• Finance — specific disclosure requirements; risk warnings
• Alcohol — must not link drinking to social success; no appeal to under-18s
• Gambling — must not encourage irresponsible behaviour; age restrictions
• Environmental claims — must be specific and substantiated

If you’re writing for any of these sectors, familiarise yourself with the relevant section of the CAP Code.

ASA rulings can have significant consequences:

• Ads must be withdrawn — immediate removal required
• Public ruling — the ASA publishes decisions, which get media coverage
• Compliance advice — future ads may need pre-clearance
• Referral — persistent offenders can be referred to Trading Standards
• Ad alerts — media owners are alerted not to run non-compliant ads

For your clients, an upheld ASA complaint means reputational damage and wasted marketing spend. Getting it right matters.

The CAP Code isn’t there to make your job harder; it’s there to maintain public trust in advertising. Ads that comply with the Code are more credible, which ultimately benefits everyone.

Your role as a copywriter is to create compelling content within these rules. When clients push for claims you can’t substantiate, that’s when your professional judgement and the Code of Practice come into play.