HomeInsightsCommittees of Advertising Practice publish advice note on verifiability in comparative advertising.


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CAP reminds readers that “verifiable” simply means setting out the relevant information about a comparative claim in an ad or signposting how the information used to make that comparison can be checked by the target audience.

The CAP Code requires that comparisons with identifiable competitor products “must objectively compare one or more material, relevant, verifiable and representative feature of those products” (Rule 3.35).

The verifiability requirement applies to all comparative ads, the note states.  Comparative advertising here means advertising which in any way, either explicitly or by implication, identifies a competitor or a product offered by a competitor.  In other words a competitor’s name does not actually have to be used for it to apply.  If an ad claims that a certain product is the cheapest in the market, or claims to run the highest ranked website or just offers a price match scheme then the comparison needs to be verifiable.

In order to comply, the ad must provide its audience with enough information about the comparison to understand it, CAP says.  If the checking requires special knowledge most consumers are unlikely to have, readers should be able to get a knowledgeable and independent person or organisation to verify the comparison using that information.

If all of the relevant information in the ad is not included (such as where detailed testing information is included) then the ad must clearly signpost how it can be obtained, CAP says.  This can be done by stating, for example, “the claim can be verified at www.[website].co.uk/comparisons” or by inviting readers to write to a postal or email address.

The nature and amount of information that must be provided will depend on the comparison being made.  If the comparison is straightforward (such as a price comparison between two products), only brief information might be needed, such as where and when the prices were checked.  For more complex comparisons (such as a grocery “swap and save” challenges involving many products), the ad might need to include a signpost to more detailed information about the comparison, including both the results and methodology.  For some claims, it might be sufficient to provide a detailed methodology only, if the results can be replicated using that information, CAP says.

CAP also reminds readers that verification information is not necessarily the same level of evidence that would be required by the ASA as substantiation for claims in an investigation.

Finally, CAP reminds readers that the ASA has previously upheld complaints where:

  • verification information was not provided;
  • the claim could only be verified by purchasing a magazine;
  • the ad contained a website address, but did not signpost that was how the claim could be verified;
  • the verification information contained inconsistencies and errors and so could not be easily understood; and
  • the verification information did not contain sufficient information.

To read CAP’s advice note in full, click here.