Has Justin Hughes (Loyola LA) solved it? He has posted Cognitive and Aesthetic Functionality in Trademark Law (forthcoming Cardozo L. Rev.) on SSRN. Here is the abstract:
This article explores trademark law’s controversial and confusing aesthetic functionality doctrine, a doctrine that has been largely unexamined in the legal literature. The article argues that the most convincing cases for aesthetic functionality aren’t really about aesthetics, but concern cognitive and psychological responses in consumers that come from evolution or acculturation. At the same time, much of the instability of aesthetic functionality case law comes from the doctrine being an unrecognized battleground in the shift from trademarks being purely indicators of source to trademarks being valuable intangibles in and of themselves. Based on these observations, the Article proposes that aesthetic functionality makes the most sense – and would be a more stable, helpful doctrinal tool in trademark law – if it is limited to situations in which the consumer preference at issue comes from cognitive, perceptual, or aesthetic biases that are widespread among consumers before the trademark owner began its own marketing efforts. The Article explores how this insight lines up with most of the aesthetic functionality case law and prevents the doctrine from being used to undermine modern marketing, branding, and trademark realities.I've bolded his proposed test. I don't have too much to say on this paper because I think this is a messy area and it will take more time and thought than I have for this blog post to parse it. Unsurprisingly, I do have a couple comments, though.