Slaughter and May is being sued for alleged negligence and breach of contract by a client that claims the firm drafted a faulty licence agreement.
Engineering and consultancy group Mott MacDonald claims the firm was negligent when it advised on a contract with David Settle over the use of his Quality Assurance System (QAS).
Mott MacDonald alleges that the contract obliged it to make indefinite royalty payments to Settle. The company claims these payments have exceeded the income from the QAS and are likely to continue to do so.
Mott MacDonald, represented by John Cayton of Cayton & Co, has filed a High Court claim asking for £150,000-£200,000 in damages.
Slaughters has instructed Barlow Lyde & Gilbert professional indemnity partner Sarah Clover.
Slaughters declined to comment on the case.