When is a faux shrug cami-top in knit fabric a "very common design" from the 1930s and 1950s aimed at the style-savvy, figure-conscious young woman with a slim budget? When it's made in Turkey and has a Savida (for Dunnes Stores) label on the back.

There's been more entertainment down at the High Court all week than a decade of Dublin theatre festivals could offer as British chain Mosaic battles to prove the originality of its Karen Millen designs and accuses Dunnes Stores of copying its originals.

This is being puffed as a "landmark" case under which Karen Millen claims its jumper and a stripy shirt, though unregistered, were still its originals and therefore shouldn't be copied. Cue faux outraged former politician-now-barrister Michael McDowell (black gown with a white shirt peeping from underneath, well cut black trousers, black shoes, black socks, no ring but a watch) to argue the case at great expense.

Dunnes Stores says it is not a copycat and Karen Millen is being more than precious by arguing that its pricy jumper and blouse are originals. Cue the faux outraged department store owner-cum-barrister Richard Nesbitt (black gown with a striped shirt peeping from underneath, well-cut black trousers, black shoes, socks, no ring but a watch).

Are they originals? Is one copying the other?

Are they both copies of some more original original?

As everyone who's ever bought a cheap Chanel "inspired" handbag on the street in Spain, a Top Shop knock-off or a Penneys "interpretation" of last week's London couture shows knows, every high street retailer plunders ideas from somebody else and recycles them as their own.

That's the beauty of buying something in Dunnes or Penneys and being able to swank around as if you're a Millen-dollar baby.