The US Supreme Court on Monday threw out an appeal by Saks Fifth Avenue and Filene's Basement Corp that they should face charges of passing off recycled wool blazers as 10 per cent cashmere.

The pair had asked the high court to overturn an earlier decision that dismissed most of the claims made by cashmere maker LW Packard & Co and cashmere makers' trade association the Cashmere and Camel Hair Manufacturers Institute.

In a six-year legal battle, the cashmere makers claim Harve Benard Ltd made, and sold, thousands of women's wool blazers that were falsely labelled as containing 70 per cent wool, 20 per cent nylon and 10 per cent cashmere.

Analysis of the garments found they contained no cashmere, and that 10-20 per cent of the fibres "were recycled, or reconstituted from the remnants of previously used or woven garments," according to court papers.

The retailers, who deny they broke false advertising regulations, will now try and resolve the matter in federal court.