New “range of factors” test suggests broad use in future civil matters and fairer, more nuanced outcomes.

By Daniel Smith and Alanna Andrew

The High Court has applied the new fact-sensitive “range of factors” test in Harb v Aziz[i] to determine whether a defendant to a civil claim can rely on the claimant’s wrongdoing to defeat the claim. The Supreme Court adopted this new “range of factors” test in the 2016 case of Patel v Mirza[ii], which replaced the “reliance test” identified in Tinsley v Milligan (widely criticised as being too formal). See Latham’s related blog, UK Supreme Court Adopts New “Range of Factors” Approach to Defence of Illegality.

The principles of the illegality defence are that a person should not be able to benefit from their own wrongdoing, and the court should not enforce claims that harm the integrity of the legal system. The defence is potentially far reaching, particularly under the new “range of factors” test, and so its recent application will be of interest to many litigants — especially if there is evidence of a claimant’s wrongdoing.