Inventor Sues Former Employer Convatec for £366 Million Over Wound Dressing Patents

An analytical chemist is suing his former employer, Convatec Ltd., for up to £366 million, alleging his patented inventions related to infection-fighting wound dressings generated billions for the FTSE100-listed medical technology company. Dr. David Parsons, who worked for the London-based firm for over 30 years after joining in 1991, claims his work created an “outstanding” benefit for the company.

Dr. Parsons' lawsuit centers on seven patent families to which he is named either solely or jointly. The inventions primarily involve the use of silver in antimicrobial plasters and dressings, notably in Convatec's Aquacel line of products for chronic wounds. These products are alleged to have generated billions of dollars for the company.

Convatec is contesting the claim, which reached London's Court of Appeal this week. The core dispute revolves around the interpretation of Section 40 of the Patents Act 1977, which allows for employee compensation if their patented inventions provide an “outstanding” benefit to their employer. Dr. Parsons is seeking a share of the profits, with earlier judgments suggesting his claim could be worth between 10 to 15 percent of the product sales value.

The company argues that for compensation to be due, the patents must be considered “outstanding” individually, rather than collectively. Convatec's legal team contends that only a truly exceptional, singular invention, a “humdinger,” should qualify for compensation, as opposed to a series of “run-of-the-mill” inventions considered together. They also argue that allowing collective consideration would unfairly benefit long-serving employees and discourage job mobility.

Dr. Parsons' legal representatives sought to have Convatec's defense struck out, asserting that the judge should have ruled on the collective consideration point rather than deferring it to the full trial. However, High Court judge Mr. Justice Mellor previously declined to make a ruling, postponing the issue until the 2028 trial.

The Court of Appeal is expected to reserve judgment on the matter. A six-week trial for the compensation claim is scheduled to take place before the High Court in early 2028. Dr. Parsons left Convatec in 2023. His initial salary in 1991 was £16,250, and he rose to become a company director during his tenure.