LOS ANGELES • Gucci's Crackle leather bomber jacket from its latest ready-to-wear collection sells for US$3,400 (S$4,600).

Forever 21's version looks like an exact copy - including the stripes motif - but is priced at US$34.90, a whopping 97 per cent cheaper.

It is one example which explains why an unhappy Gucci has taken the American fast-fashion retailer to court in California.

The Italian fashion house alleged that its trademarks of more than 50 years' standing - such as stripes of green-red-green and blue-red-blue - have been reproduced in Forever 21's clothes.

It is alleging trademark infringement, trademark dilution and unfair competition.

But Forever 21 is fighting back by suing Gucci over the right to use the stripes.

Its defence is that "many clothing and accessory items adorned with decorative stripes coloured bluered-blue or green-red-green are sold by countless third parties. Gucci should not be allowed to claim that Gucci, alone, has a monopoly on all blue-red-blue and green-red-green striped clothing and accessory items".

Hollywood Reporter cited Ms Julie Zerbo, founder and editor-in-chief of The Fashion Law, as saying any judgment could hinge on whether consumers are likely to be confused by the similar-looking versions.

"Are they going to think that Gucci has authorised this use?

"Have they licensed this?

"Have they collaborated?"

Forever 21 is also being sued by adidas, which objects to its use of a three-stripe design on apparel, athletic wear and shoes that is similar to the German brand's own iconic three-stripe trademark.

Millions of dollars in earnings are at stake, as well as the preservation of brand value.

However, industry experts do not expect a bruising battle ahead, with the cases likely to be settled out of court among the parties.