Warren Buffett remarked that 'only when the tide goes out do you discover who's been swimming naked'. Professionals may – rightly or wrongly – be targets for the deflection of some of the ensuing embarrassment. Professional negligence claims are already on the increase.

Since the last boom in professional negligence claims (which led to developments in the applicable law) developments in other areas have occurred that will impact the professional negligence sphere. One important development concerns the circumstances surrounding the settlement of claims involving multiple professional defendants.Take a complex corporate transaction involving lawyers and accountants, corporate financiers and numerous consultants. After completion, a problem emerges that was missed by the lawyers and accountants and undervalued by the consultants. The 'loss' is the overpayment of the price for the shares. The shared responsibility involves parties with different approaches to claims and varying perceptions of the merits, each looking to pass the buck.

If the victim of the negligence proceeds against all possible defendants, can he 'pick off' one at a time? What is the effect of settlement with one defendant on the claims against – or between – the others?

In Jameson, the House of Lords was faced with a situation where an action in respect of industrial injury could have been brought against a series of employers responsible for the system within which the injured Mr Jameson worked. An action was brought against one employer for the full extent of Mr Jameson's injuries. The claim was for £x and settled for £y (less than x) before the question arose whether it was permissible for Mr Jameson's estate, following his death, to bring a second claim against another employer for the difference between x and y.

The House of Lords decided that there was no proper second claim, given that the process of settlement of the first claim (which was for the full extent of Mr Jameson's losses) involved a valuation of the amount of the claim which took account of the contrary arguments to success, the strength of the evidence and other factors. Payment of £y to Mr Jameson therefore represented the full extent of this revalued loss and the entirety of the claim was discharged.

Good news for both the second and the first defendant: the first employer was no longer exposed to the claim from Mr Jameson or to the potential claim from subsequent defendants (other employers liable in respect of the same damage) who might seek a contribution for the same loss under the Civil Liability (Contribution Act) 1978.

The legal basis for Mr Jameson's claims was a claim in tort for breach of the statutory duty of care. All those employers responsible for him over the years were joint tortfeasors.

But does this outcome mean if A has settled a claim in tort with B, he can't sue C?

In Heaton v AXA Equity & Law Assurance Society it was held that A can, but only for nominal damages, since he has recovered his full loss under the settlement. B can, however, recover a contribution from C under the 1978 Act. This is no general rule but depends on the terms of the settlement of the first claim, bearing in mind the release of one concurrent tortfeasor or contract-breaker doesn't have the effect in law of releasing another, and an agreement made between A and B will not affect A's rights against C unless either A agrees to forgo or waive rights he would otherwise enjoy against C, or the agreement falls within that limited class of contracts which is enforceable by C as a third party.

The law is clear that settlement agreements will be construed in the same way as other contracts, and it will be incumbent on the settling claimant in the agreement not to compromise his rights to proceed against anyone else.

Jon Fortnam is a commercial litigation partner at Pinsent Masons.