In Willmott Dixon Construction Ltd v Robert West Consulting Ltd  EWHC 3291 (TCC), Coulson J gave guidance as to the exceptions to the general rule that a main contractor cannot be liable in tort for the acts or omissions of an independent sub-contractor. He also analysed the application of those exceptions to a plea of contributory negligence.
Coulson J’s judgment establishes that a court cannot find contributory negligence against a claimant by reason of acts or omissions of the claimant’s independent contractor unless it also finds some fault on the part of the claimant itself. The question of whether an employer owes a non-delegable duty of care to a third party in respect of the acts of its independent contractor has nothing to do with the law of contributory negligence.
The claim was for damages for negligent design of a construction project which led to damage to a party wall. Robert West were sub-contracted by Willmott Dixon to design the project, whilst the party wall works themselves were carried out by another sub-contractor.
In its Defence, Robert West asserted that the damage to the property was caused by negligence on the part of Willmott Dixon’s works sub-contractor. Rather than bringing a Part 20 claim for a contribution against that works sub-contractor, however, instead it alleged that the negligent works comprised contributory negligence on the part of Willmott Dixon, notwithstanding that the works had been carried out by an independent sub-contractor. In a Further Information it accepted the general rule that an employer is not liable in tort for the acts or omissions of an independent contractor but alleged that the case fell within the exception to that general rule set out in D&F Estates v Church Commissioners for England  AC 177, i.e. it alleged that Willmott Dixon knew about and condoned the negligence of its works sub-contractor (because it supervised the works). It also made it clear that it did not seek to allege that Willmott Dixon was vicariously liable for the acts of its works sub-contractor.
About a month before trial, Robert West applied for permission to amend its Further Information so as to delete its concession that Willmott Dixon was not vicariously liable for the acts of its works sub-contractor and to add reliance on a further ‘exception’ to the rule that an employer is not liable in tort for the acts or omissions of an independent contractor. The new exception it sought to rely on was that set out in Alcock v Wraith  BLR 20 and Johnson (t/a Johnson’s Butchers) v BJW Property Developments  3 All ER 574, pursuant to which an employer owes a non-delegable duty of care to his neighbor in respect of any acts or omissions of an independent contractor where that contractor is entrusted with works which involve the withdrawal of support from the neighbouring property.
Coulson J refused permission for either amendment. He stressed the importance of distinguishing between non-delegable duties and vicariously liability, relying on the speech of Lord Sumption in Woodland v Essex County Council  AC 537 in which he made clear that an employer can never be vicariously liable in tort for the acts or omissions of an independent contractor. The only true exception to the rule that an employer is not liable for the acts or omissions of an independent contractor is where the employer owes a non-delegable duty of care to a third party, which is analogous to a contractual duty to ensure an outcome. In those cases, the employer is liable to the third party by reason of its breach of that duty owed directly to the third party, not because of its relationship with the contractor.
Moreover, when an employer owes a non-delegable duty to a third party, it is liable if the contractor is negligent without any need to show that it was negligent itself: indeed, if it were negligent itself, there would be no need to rely on the non-delegable duty. By contrast, contributory negligence depends upon a defendant showing that a claimant has failed to take reasonable care to protect itself (see e.g. Standard Chartered Bank v Pakistan National Shipping Corporation and others (No 4)  QB 167 per Ward LJ at p193). Accordingly, Coulson J held that the question of whether Willmott Dixon owed a non-delegable duty to the owner of the neighbouring property under the Alcock exception was a red herring when it came to Robert West establishing contributory negligence against Willmott Dixon: to do that, it must establish some fault on Willmott Dixon’s part. Establishing fault on the part of its independent contractor would not suffice.
It therefore followed that the amendments had no real prospect of success. Coulson J also noted that Johnson (t/a Johnson’s Butchers) v BJW Property Developments (which Robert West had sought to rely on) wrongly elided the concept of non- delegable duties and vicarious liabilities and was, in his view, no longer good law.
 Coulson J held had this was a separate exception to the ‘extra-hazardous activities exception’ addressed by the Court of Appeal in Biffa v Maschinenfabrik  QB 725 and, accordingly, was not subject to the limitations set out in that case.
2TG’s Joe Sullivan appeared for Willmott Dixon in the TCC.