Christian Louboutin, the footwear designer, is known for his distinctive, red-soled shoes, worn by the likes of Angelina Jolie and Kylie Minogue and retailing at up to £700.

Louboutin's eyecatching red soles link the shoes to the designer, giving the product a distinctive look and feel, or “trade dress”. Yet close copies of Louboutin's creations can be found for sale on shopping websites for a tiny fraction of the price.

Although such design features are seen as the best way to associate the product with the brand in consumer minds, as an asset such trade dress often goes unprotected. According to research published this month in the Harvard Business Review, small or medium-sized companies neglect to register design features as trademarks, put off by the costly, lengthy process. Betsy D. Gelb and Partha Krishnamurthy, researchers from the CT Bauer College of Business at the University of Houston, report that many believe - mistakenly - that the chances of being copied are slim and that they can sue imitators who attempt it. But being the first to be linked with a design feature is no guarantee that others cannot copy it legitimately.

In the United States in 2000, Samara Brothers, a clothes wholesaler in New Jersey, was unable to prove in court that its children's clothing designs were associated with only one brand source. As a result Wal-Mart, the supermarket giant, was able to sell very similar items. The ruling highlighted the importance of acquiring evidence that consumers recognise a design feature as belonging to one brand.

To protect their products, the writers suggest that companies should conduct research to establish how valuable particular design features are. A marketing campaign may strengthen the connection, discouraging imitators and improving the chances of success in a legal contest, they say.

In the UK, laws on protecting design features, often referred to as “get up”, are similar. “The fact that you are the first to make something doesn't secure exclusivity,” Rachel Bunn, head of intellectual property at the Waterfront Partnership, a legal practice, said.

Companies cannot rely on consumer research to protect them if they do not have appropriate rights, such as trademarks. “The terms of how the research was conducted would need to be legally approved to ensure there was no bias,” Ms Bunn said, advising companies to register both trademarks and design rights.

This not only protects companies against would-be imitators but also ensures that a company owns a design. In the case of design features that are not registered as trademarks, being able to prove a “goodwill element” - that consumers buy that product because of a distinctive facet, such as Louboutin's red soles - may be enough to make a case.

Times Recommends

• Minister in talks with Saudis to protect creditors
• Premier Inn hits back in £29-a-room row
• Bankers hit back at 'populist' bonus supertax