Me and my client, we're buddies, alright? It's one terrific partnership. Of course we trust each other, adore each other … contract? Pah! Hang on, I'm liable for what…?

If partnering as a procurement method has not exactly come of age yet, it has at least matured since those early days when the first edition of the NEC contract was published. It can take many forms. The GC/Works/1 approach is to add a "fair dealing and teamworking" clause and then leave the rest of the contract largely unaltered. At the other extreme PPC2000 integrates the professional team, the contractor and at least some of the subcontractors into the same contract. Despite this variety there is a recognition that partnering is a credible way of procuring construction. What works for Heathrow Terminal 5 can also work at the smaller end of the market.

There was some doubt about whether the courts would accept the legal validity of the necessarily vague concepts that partnering involves: mutual co-operation and trust for instance. In practice, however, the courts have gone with the flow: in Birse Construction vs St David the judge said: "These days one would not expect where the parties had made mutual commitments such as those in the Partnering Charter … to be concerned about compliance with contractual procedures [as long as] there had been true compliance with the letter or the spirit of the charter."

So what does all of this mean for design liability? Clients and designers are used to working collaboratively, in the early days of their relationship at least. The exact terms of the appointment are crucial, though. In those situations where the contract says nothing about standard of care, there is an implied duty of reasonable skill and care. Where there is a partnering contract, the level of design risk may be that of reasonable skill and care, or it could be strengthened slightly by the common provision that the reasonable skill and care be that of a designer who is skilled and experienced in designing the particular structure that is the subject of the project.

In a partnering contract there should still be some way of identifying exactly what services the designer is to provide. This is a key component of any appointment, and it is particularly important with partnering, when there may be some blurring of the edges between the work of different designers. There are always interfaces that require co-ordination, whatever form of procurement is used.

The great advantage of partnering is that all the parties are expected to work together to solve any design issues that may come up. This is good from the designer's point of view and from the client's. It should mean that the completed structure is more satisfactory and that there is less wastage in terms of abortive work in dealing with design issues.

The question of liability in a partnership can be difficult: if the parties have collaborated and the solution does not work, who is to blame?

The question of liability in a partnership, however, is more difficult: if the parties have collaborated to achieve a design solution to deal with a particular issue, and that solution does not work, who is liable?

In practice it may be difficult to work that out. Some contracts list the services for individual designers, add partnering concepts and hope for the best in terms of resolving liability issues if they should arise. Other contracts arrange to share pain and gain, so that if there is a problem, whether of design or anything else, the pain is shared in pre-agreed proportions among all the partnering members, including the client; if savings are made, these will similarly be shared.

There is another aspect to design liability in those projects where the partnering provisions have been bolted on to a more traditional approach. If the partnering arrangements work, there is no problem. If they do not, there can be serious and expensive arguments. At this point the partnering arrangements can be a double-edged sword. In Birse where there was an argument about whether the letter of intent was contractually binding, the judge said that "people who have agreed to proceed on the basis of mutual co-operation and trust, are hardly likely at the same time to adopt a rigid attitude as to the formation of a contract". So he did not accept arguments that there was no contract.

The message therefore is clear: even if you are working with your client on a partnering basis, it is still worth having a formal contract, and looking at the clauses in detail to see that you know what the standard of your duty of care is, that you understand what time constraints you will be working to and what the content of your work is to be (that is, your services). Equally, it is important to realise that if you are contractually obliged to co-operate, you need to take that obligation seriously. It will not work, and could involve you in greater liability, if you treat the contract like a traditional form.