Contingency fee payments for expert witnesses look set to be outlawed in a new code of conduct that is designed to stamp out the 'hired gun' image of many experts.

The clause banning payments to experts based on the outcome of a case is contained in a draft code of conduct that was unveiled by the Master of the Rolls, Lord Phillips, at a conference organised by expert witness training company Bond Solon on 9 November.

Clause one states experts are 'under an overriding duty to help the court deal with the case justly'.

The draft code goes on to stress that this duty is incompatible with payments 'contingent upon the nature of the expert evidence given in legal proceedings, or upon the outcome of the case'.

Its publication follows two-and-a-half years of wrangling between the two bodies that represent expert witnesses – the Expert Witness Institute and the Academy of Experts – over the exact text of the code.

Lord Phillips told the conference: "It is very unfortunate that you have two bodies which are competing rather than co-operating." He added that the code would be published within weeks and warned that experts and solicitors that breached it risked having evidence struck out and being penalised over costs.

Mark Solon, director of Bond Solon, said: "Solicitors and experts have been operating in a vacuum since the Civil Procedure Rules were published. Now, at last, they are getting some instruction on how they should operate."