Nike became the first UK company to have a Twitter campaign banned when the ASA cracked down last month on the following tweets the footballers published in January.
Wayne Rooney tweeted: "My resolution – to start the year as a champion, and finish it as a champion….#makeitcount gonike.me/makeitcount".
Jack Wilshere tweeted: "In 2012, I will come back for my club – and be ready for my country. #makeitcount.gonike.me/Makeitcount".
Makeitcount is the name of a Nike Twitter-centric campaign devised by AKQA.
The ASA investigated after one complaint that challenged whether both tweets were identifiable as marketing communications.
It ruled that in the absence of a marker, for example #ad, the tweets were not obviously identifiable as Nike marketing communications and therefore breached the CAP Code rules on recognition of marketing communications.
However, Nike has yet to remove the tweets despite the ASA’s ruling they should no longer appear, because it is invoking the watchdog’s own appeals process.
Advertisers or complainants are able to ask the ASA’s Independent Reviewer to study a ruling. Should the independent reviewer feel the ASA Council should reconsider a decision he is able to suggest it does so, although his recommendation is non-binding.
The process was employed in May in relation to Channel 4’s ‘Bigger. Fatter. Gypsier’ ads, resulting in the ASA changing its original decision not to investigate them.
Given the growing importance of Twitter as a platform for celebrities to promote brands, the fate of Nike’s appeal will be of interest across the industry.
A spokesman for the sportswear brand said it does not believe that Rooney and Wilshire’s Twitter followers were misled "because it was clear that the messages were connected to Nike’s Make It Count message".
It also claims the judgement of the initial ASA examiner on the case "was that the tweets were clear and not misleading about their connection to Nike's Make It Count campaign".
However, it is understood that it is not unusual for ASA draft recommendations to be along different lines to what is finally agreed by the ASA Council.
It is worth noting the ASA has previously taken the advertiser’s side in a similar but subtly different case involving Rio Ferdinand and Katie Price tweeting as part of a Snickers campaign.
Ferdinand and Price seemingly wrote out-of-character "teaser" tweets about knitting and the economy, before posing pictures of themselves with the chocolate bar.
The tweets were investigated over two possible breaches of the advertising code: whether it should have been stated in the "teaser" tweets that they were marketing communications; and whether the hashtag "#spon" in the final "reveal" tweet made it clear enough that that tweet was a marketing communication.
The ASA ruled in favour of Snickers owner Mars, saying it had not breached the CAP Code. It came to the decision because it said that Mars had made clear that the fifth and final tweet was an example of advertising, as it had included the text, "You're not you when you’re hungry @snickersUk #hungry #spon …"
Follow Daniel Farey-Jones on Twitter @danfareyjones