When proof is a burden

Marcus Cooper and another v Thameside Construction Company Limited [27.05.16]

The Technology and Construction Court considers competing theories as to ‘who dunnit’. Standing back and looking at all the evidence the Judge held the claimants had not made out their case on a balance of probabilities. The claimants had failed to discharge the burden of proof. Kennedys acted for the successful defendant.


The claimants converted 22 Redington Road, Hampstead, from four flats to a family home. On 18 November 2010 the house was flooded. Insurers’ settled the claimants’ £10 million property and contents claim for £6.5 million and commenced subrogated proceedings to recover their outlay.

It was common ground that the flood was caused by the hot water pipe beneath the basin in bathroom six separating from a Polyplumb straight connector (the connector). It was also common ground that the defendant had sub-contracted the plumbing to Darenth.

The key issue in the case was who fitted the connector? The claimants argued that the connector could only have been fitted by Darenth because Darenth were the only contracted plumbers on site. Darenth denied they installed the connector which had no obvious function in that location and argued that others had carried out various works beneath the basin subsequent to Darenth completing their plumbing works in the bathroom.

The burden of proof

In Rhesa Shipping v Edmunds (the Popi M) [1985] it remained in doubt why the Popi M sank in calm waters. Mr Justice Bingham chose between two remaining and competing theories on causation. He opted for the claimant ship owners’ extremely improbable theory that the ship was sunk by a submarine over underwriters’ virtually impossible wear and tear theory. When the case reached the House of Lords, Lord Brandon considered the proper approach to causation and rejected Sherlock Holmes’ dictum (followed by Bingham J) that “when you have eliminated the impossible, whatever remains, however improbable, must be the truth.”

Lord Brandon held that:

  • Before finding that a particular event occurred the judge must be satisfied on the evidence that it was more likely to have happened than not.
  • A judge is not bound to make a finding of fact one way or the other.
  • There is a third alternative, namely it is open to the judge to find that the party on whom the burden of proof lies has failed to discharge that burden. That reasoning was followed by the Court of Appeal in the recent case of Graves v Brouwer [2015].


In the present case, the Court held it is clear that the burden of proof stays with the claimants throughout to show on the balance of probabilities that the defendant or its subcontractor(s) had installed the connector. Although it was open to the defendant to put forward a competing theory or theories, there was no obligation on the defendant to identify, on a balance of probabilities, when or by whom the connector was fitted.
Mrs Justice Carr found that the forensic exercise in reaching findings of fact in this case had been hindered by the absence of material witnesses and that all the facts and possible explanations were not before the court. She found on a balance of probabilities that Darenth did not install the connector. There were at least two real possible alternative explanations as to why the connector was installed which did not involve the defendant. On the state of the evidence it was at least possible that a third party had installed the connector; installing the same was a relatively simple task which could have been done by a non-plumber.

The mystery remained unsolved. As the case against the defendant had not been made out on a balance of probabilities, the claim was dismissed.


This case illustrates that where there are gaps in the evidence before the court and competing theories as to what events happened and why, the burden of proof remains with the claimant throughout the trial to prove its case on a balance of probabilities. Significantly, it is not open to the claimant to transfer the burden of proof to the defendant seeking to put the onus on the defendant to disprove the claimant’s theories.

The judge can only eliminate competing theories if all of the facts are known. But even if at the end of the day there is one preferred explanation, the judge must stand back and consider if that version of events is more likely than not to be the truth.

In contrast, where there are gaps in the evidence it is open to the judge not to make a finding one way or the other and in those circumstances conclude the claimant has not proved its case on a balance of probabilities. This case is a reminder that evidential proof can be a burden for a claimant.