So, does Adidas have a case for copyright infringement? The American sportswear company is relatively litigious over such issues - most recently taking Payless Shoes to court in 2008 to protect key design features including the "coloured portion on the outer back heel that identifies the shoes as Adidas's brand".
"Given Adidas's federal registration and because the Isabel Marant Bart shoe employs a very similar design element, the heel tab - one that is arguably employed by Adidas to serve as an indication of source - Adidas very well may have a merited infringement claim," The Fashion Law comments. "After all, the two brands' heel tabs look pretty similar. Adidas's Stan Smiths come in a red variation with 'Stan Smith' written in white, along with the Adidas logo. Marant's are a metallic red with 'Isabel Marant' written in white. The fonts, however, are a bit different, as is the size of the text. Moreover, while Adidas uses a darker thread to secure its heel patch, Marant uses white thread. These things matter in the similarity inquiry."
The most important point in trademark infringement cases is whether or not the similarity is likely to cause customer confusion between Adidas's £62 trainers and Marant's £270 one - and whether that confusion could in any way damage sales of the plaintiff's products. Since the Bart is already being stocked by Barneys, Net-a-Porter and Luisa Via Roma among others, it's fair to assume that customers - who could potentially wear the Stan Smiths - are now wearing the Marants. And since Adidas are in the habit of collaborating with designers - Mary Katrantzou, Kanye West and Jeremy Scott among others in recent months - there is a chance that customers could assume that the Marant shoes have in fact been created for Adidas.
Neither brand made any comment when contacted this morning.