Over the last week, Colin the Caterpillar has received plenty of attention in the UK media, following the launch of a trademark action by elegant middle class retailer Marks and Spencer against budget end Aldi. Colin is a classic children's birthday cake, and Marks and Spencer are presumably unhappy about the rather similar Cuthbert caterpillar cakes sold by Aldi, and perhaps about the caterpillar cake offerings by several other supermarkets. My colleague Donna Trysburg has already provided an excellent initial report on the matter here.

I spotted a short interview broadcast by the BBC with the self-styled Judge Rob Rinder, both TV lawyer and trained barrister, in which he expressed sympathy with Aldi and the other copycat(erpillar)s. No problem there, but I could sense my IP attorney colleagues across the country cry out with joy when Mr Rinder explained that “Marks and Spencer’s are saying this is a cake, which is under the guise of the same standard, in other words people will be confused if they buy Cuthbert, they’re going to think its precisely the same thing as the one that’s sold in M&S, and that’s creating sufficient confusion that Aldi are in breach of copyright.

For an IP attorney, this a most delicious mix up between two completely different IP rights: trademarks which involve the concept of consumer confusion, and copyright which does not, and is only slightly short of the classic patent attorney joke “I’d like to patent the copyright in my trademark please”.

This might all seem a bit pedantic, but pedantry is an area in which we patent attorneys excel, and it can be very important. When it comes to arguing that an invention is patentable over the "prior art", i.e. everything already known to the public, there are two main hurdles: novelty (how is the invention different from the prior art?) and inventive step (is this difference enough to justify a patent?) although terminology differs a little around the World.

Before the European Patent Office, keeping a clear and pedantic separation between novelty and inventive step can be crucial, especially when a case is under detailed scrutiny in a tough post grant opposition, or during an appeal. However, the truly artful patent attorney appreciates that the boundary between novelty and inventive step can be flexible, or at least presented in different ways.

The EPO tends to use a “problem and solution” approach to inventive step. A “closest prior art” document is selected and compared in detail with the claims of the patent to establish very precise reasons why the invention is “novel” over that prior art. However, a creative patent attorney knows how to interpret both the closest prior art, and the patent claims, in subtly different ways to support the desired patentability narrative.

Arguing that a completely different document is the “closest prior art” is another way to repaint the inventive step argument, but even subtle shifts of light and perspective in the novelty story can lead to different shadows being cast by the boundary fence of novelty onto the inventive step space beyond.

So next time a European Patent Attorney you know or work with seems to be chronically pedantic about something, please be forgiving - it comes with the job.

I did visit my local Aldi yesterday, but Cuthbert was unavailable for comment.