An inventor who says his work on a high-tech sticking plaster helped earn billions for his bosses is suing for up to £366million, asking for a share of the profits.
Analytical chemist Dr David Parsons worked for FTSE100-listed Convatec Ltd for more than 30 years, having joined the London-based medical products and technologies firm in 1991.
Starting out on a yearly salary of £16,250 before rising to become a company director, Dr Parsons went on to put his name to multiple patents for inventions.
The business used these in creating some of its high-tech Aquacel wound dressings.
The inventions mainly related to the use of silver in infection-fighting antimicrobial plasters and dressings, said to have netted the company billions.
Dr Parsons, of Hoylake in Merseyside and who left Convatec in 2023, is now suing for compensation of up to £366million at the High Court.
He says his work created an 'outstanding' benefit for his employer.
Convatec is fighting the claim, which reached London's Court of Appeal this week as the two sides argued over the issues to be determined when it reaches trial before the High Court in 2028.
Analytical chemist Dr David Parsons is pictured outside London's Court of Appeal
Convatec's Aquacel AG+ product, named in Dr David Parsons' lawsuit
Setting out the background to the dispute, Dr Parsons' barrister Patrick Green said the case revolved around seven 'patent families' in which he is named either solely or jointly.
Mr Green told the court: 'During his employment, Dr Parsons made a number of inventions, upon which patents have been granted and which, as between Dr Parsons and Convatec, belong to Convatec and have led to a succession of successful products made by Convatec, pleaded to have generated billions of dollars.
'He pleads to benefit from the products which rely upon the patents and inventions, as being "at high profit margins and very high rates of return on the costs of making the underlying inventions".'
Much of Dr Parsons' work related to the use of silver in the company's 'hugely successful' Aquacel line of infection-fighting dressings for chronic wounds.
He is suing for compensation under Section 40 of the Patents Act 1977 on the basis that the patents to which his name is attached – considered individually or collectively – created an 'outstanding' benefit for his employer.
In a judgment during an earlier stage of the dispute, Mr Justice Richards said Dr Parsons' claim to 10 to 15 per cent of the value of sales of the products could mean that 'could be worth up to £366million'.
The case is set for a six-week trial in 2028, with issues surrounding what work was done by Dr Parsons and how it benefited the company due to be decided.
As well as questioning the exact impact of his work, Convatec argues that the effect of the patents on which Dr Parsons is named have to be considered 'outstanding' individually – rather than collectively – in order for compensation to be due.
The company says only a 'humdinger' one-off invention can result in compensation to an employee, as opposed to a long list of 'run-of-the-mill' inventions considered collectively.
The case went before a High Court judge earlier this year, with Dr Parsons asking for that part of Convatec's defence to be struck out, arguing it was wrong that his work could not be considered collectively.
After High Court judge Mr Justice Mellor declined to make a ruling on the issue, putting it off until the full trial of the claim in 2028, the case went to the Court of Appeal this week.
In court, Dr Parsons' barrister Mr Green argued that Mr Justice Mellor was wrong not to decide the point there and then and should have struck out that part of Convatec's defence.
Mr Green said: 'In short, the learned judge was wrong not to decide the point and to leave it hanging in the air, to be argued all over again at trial.
'Dr Parsons's application should have been both decided and granted, not deferred to be argued all over again at a trial.
'There was only one answer as a matter of law and the judge should not have let a plea that was bound to fail proceed to trial – especially having heard argument upon it and a hearing at which the application was listed to be determined.'
But quoting the then Lord Chancellor, Lord Elwyn-Jones, in Parliament when the Patents Act was discussed in the 1970s, Convatec barrister Brian Nicholson said compensation would be due only for the most exceptional inventions.
He said: 'What is required in order for an employee to be entitled to compensation is a "humdinger" of a winner of an invention of the sort which "may revolutionise a company or perhaps even a whole industry", as distinct from "run-of-the-mill inventions which are patented by the thousand every year".'
Mr Nicholson said that if the law allowed pieces of work to be considered collectively, as opposed to individually, it would unfairly favour long-serving employees.
He said: 'They would be favoured over employees who moved to a new employer, thus discouraging employees from moving between companies.
'The appellant's approach would constitute a significant disincentive to the long-term retention of employees.'
Judgment in the appeal before Lady Justice Asplin, Lord Justice Baker and Lord Justice Arnold is likely to be reserved until a later date.
The full trial of Dr Parsons' compensation claim is due to go before the High Court early in 2028.