The Langholm-based firm is charged with falsely claiming scarves were 100% cashmere on two occasions in 2014.
The alleged offences are said to have taken place at the company's store in Church Place, Dumfries.
Edinburgh Woollen Mill has denied the charge, brought under the Textile Products Regulations 2012.
A trial began at Dumfries Sheriff Court earlier this year and it heard from defence witness Dr Philip Greaves this week.
The textile fibre analyst tested samples of the red and blue scarves at his own facility and found them to be 96.7% and 97.2% cashmere, he told the court.
He said EU and UK standards allow for a 5% tolerance when labelling products.
Asked by defence QC Susan Duff if his findings would allow the scarves to labelled as 100% cashmere, he said: "In terms of regulations, yes.
"There's an industry expression: commercially pure."
Dr Greaves, described as a "world leader" on the subject, said other materials found in the scarves were "inadvertent impurities" which can become part of the product during manufacturing or packaging.
He said: "A block of steel will remain pure but textiles pick up material along the way, and that's why there's a tolerance of certain percentages."
When asked about the results of tests from other labs which found the scarves to contain only 84.4% and 61.6% cashmere, Dr Greaves said bleaching of materials can make them hard to identify as cashmere.
"I think that they perhaps did not recognise the bleached cashmere fibres," he said.
Questioned by fiscal depute Alison Herald about the other examiners, Dr Greaves said: "There's nothing to suggest that they are not skilled but perhaps they are not experienced in fibre damage and this particular bleaching of cashmere."
A second defence witness, Mary Lunn, who tests Edinburgh Woollen Mill fibres for TFT Ilkley, told the court her examination of the scarves found them to be both 100% cashmere.
Asked about the difference with Dr Greaves, she said: "That's within the acceptable range, I would say."
Questioned by Ms Duff on the two lower cashmere results, Ms Lunn said: "Obviously they haven't done it right, in my opinion.
"There's no way there could be that much variation, 2% to 4% maybe, but not that much."
The trial continues.

The first was for the development of tidal arrays in Alderney's waters.
The second involves the development of an electricity interconnector cable between France, Alderney and Britain.
Paul Clark, chief executive officer, said it was a move towards the creation off Alderney of one of Europe's largest tidal stream developments.
Alderney Renewable Energy (ARE) was set up in 2004 and holds an exclusive licence to commercially develop tidal and wave power around the coast of the northern most of the Channel Islands.
The first agreement was signed with French industrial group DCNS and the second with ARE, its partner Transmission Capital and the French grid operator RTE.
ARE said the electricity interconnector cable between France, Alderney and Britain would enable the export of up to four gigawatts of tidal power from Alderney.
It said the cable, known as the FABLink, could also be used as a power trading link between the two countries.
The agreements were signed at the Anglo-French summit held in Paris, with the French Industry Minister Eric Besson and the UK Energy Secretary Ed Davey signing on the behalf of their governments.
Mr Davey said: "We are determined to promote the potential of marine energies. We welcome the plan for a tidal turbine farm off Alderney in the Channel Islands."
He said: "We believe this project could encourage the emergence of industrial co-operation between France and the UK, while opening up new international prospects.
"We acknowledge the importance of developing new electricity interconnectors between our two countries in order to strengthen further the linking of our grids, improve the security of our energy supplies and facilitate the integration of intermittent energy sources."
Edinburgh Woollen Mill scarves claimed to have been mislabelled were correctly marked as 100% cashmere, a testing expert has told a court.
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Two agreements have been signed aimed at creating one of the most significant tidal power sites in Europe, Alderney Renewable Energy has announced.