"While the use of a clan tartan would appear to be aesthetically functional for traditional Scottish clothing such as kilts, the concept of aesthetic functionality is not well accepted, ... and it is inconsistent with the concept of a collective mark and should, therefore, not be applied to such marks".The IPKat agrees that the concept of "aesthetic functionality" is a tough one to grapple with -- yet in the context of design right it is a notion that lies right at the heart of the question of how one identifies protectable subject-matter. In European trade mark terms too, we are coming to terms with the notion that the aesthetic/functional continuum ranges from (i) aesthetic but non-functional, (ii) aesthetic and functional to (iii) functional but not aesthetic. At times like this, conferring protection on the basis of broad principles of unfair competition rather than as a result of fine discrimination between types of subject-matter looks the best approach.
Make your own Tartan here; identify existing Tartans here
Tartan Day here; Tartan Army here