The Supreme Court rejected the suggestion that because BDW had sought to repair defects on developments no longer owned by it and without any enforceable legal obligation to do so, such economic losses (by completing repair works) were voluntary and could not be recovered.  They said that there was no rule of 'voluntariness' which meant the repair costs were outside the scope of the duty of care owed by URS or too remote to be recovered.

In any event, the Supreme Court considered that, given the circumstances, it is strongly arguable that BDW was not acting voluntarily at all as:

a) if BDW did nothing to effect repairs, there was a risk that the defects would cause personal injury to, or the death of, homeowners for which BDW might be legally liable;

b) BDW had a legal liability to the homeowners under the DPA or in contract to incur the cost of repairs, as, even though at the time the repairs were carried out the claims by the homeowners would have been time-barred, limitation bars the remedy but does not extinguish the right; and

c) there would be potential reputational damage to BDW if BDW did nothing once it knew of the danger to homeowners; it was therefore in BDW’s commercial interest to effect the repairs.

The Supreme Court concluded that there is "a strong case for contending that BDW was, in any event on the assumed facts, not exercising a sufficiently full and free choice so as to be regarded as acting voluntarily in effecting the repairs. In other words, BDW had no realistic alternative. The three features indicate that BDW was not, in any true sense, acting voluntarily."

The Supreme Court did go on to state that 'voluntariness' may yet be relevant to issues of legal causation or mitigation on the specific facts of each case.  How this is applied in practice remains to be seen, but it may prove difficult to argue that a developer acting 'voluntarily' did not act reasonably as a consequence of the defects for which another party is responsible.  This is particularly so in light of the Supreme Court's comments that they had reflected on the policy consideration of "achieving a fair and reasonable allocation of the risk of the loss that has occurred as between the parties" in deciding these points. The policy clearly favours incentivising a claimant in BDW's position to carry out the repairs so as to ensure that any danger to homeowners is removed, and that in doing so BDW should not then be penalised.