Civil Liability Act 2002

In a proceeding relating to liability for breach of duty –

the fact that a risk of harm could have been avoided by doing something in a different way does not of itself give rise to or affect liability for the way in which the thing was done; and the subsequent taking of action that (had the action been taken earlier) would have avoided a risk of harm does not of itself give rise to or affect liability in relation to the risk and does not of itself constitute evidence of liability in connection with the risk.