There is a fine line in fashion between what breaches copyright and what does not. Many design rooms for large companies work by taking clothes that are already on the market and designing around them or with them closely in mind. It is no surprise that consumers often find the stock of one shop varies only slightly from that of another. And as clothes on the catwalks increasingly follow the pared-down silhouette of Calvin Klein, they seem, superficially at least, easier to copy.

Antoni & Alison were thrust into the limelight in 1993 when they took Giorgio Armani to court over a T-shirt. The case was settled out of court, but since then, the designers feel their work has become public property. Some rip-offs of their vacuum-packed slogan T-shirts now on the mass market, are, says Antoni, "really nasty. People think we've designed these things."

Antoni & Alison have also taken legal action against the French chain Morgan, which has been selling T-shirts in vacuum wrapping, Antoni & Alison's trademark. Morgan has subsequently redrawn the T-shirts. Jeffrey Rogers denied having heard of the designers when they complained about T-shirts bearing their slogan, "Love it". The copies used an extra fullstop and a slight change of typeface.

"Good luck to Liza Bruce," says Antoni. "More designers just have to stand up and say stop. Hopefully, it will embarrass the large stores, and make shoppers aware of what really goes on." However, with changes to the rules governing legal aid, Antoni says, there needs to be a free fashion advisory service to deal with cases such as this.

According to Stuart Lockyear, a partner with Stephens Innocent, the law firm which works with Antoni & Alison and which has taken on Liza Bruce's case,breach of copyright depends on whether you have copied, not the idea, but the substance of a garment. If the second garment is held up against the original and could not have been conceived or designed without it - when the second garment combines the same colours, the same cut, and fabric - Lockyear considers there to have been copyright infringement.

Theft of ideas, designs, colourways and fabric suppliers is so widespread that one designer saysthat if Bruce wins her case, her company will take on the whole high street.