In its 2011 report “Expert Evidence in Criminal Proceedings in England and Wales” (Law Com No.325), the Law Commission recommended that the admissibility of expert evidence in criminal proceedings should be governed by a new statutory regime comprising a new statutory reliability test in combination with codification and refinement of existing common law principles relating to “assistance”, “expertise” and “impartiality”. The Government declined to enact the Law Commission’s draft Bill due to a lack of certainty as to whether the additional costs incurred would be offset by savings. Instead the Government invited the Criminal Procedure Rule Committee (CrimPRC) to consider amendments to the Criminal Procedure Rules (CrimPR) to introduce, as far as possible, the spirit of the Law Commission’s recommendations. The consequent amendments to CrimPR Part 33 (now CrimPR Part 19) in combination with the making of the new Practice Direction CrimPD 33A (now CrimPD 19A) by the Lord Chief Justice, resulted in what he described in his 2014 Criminal Bar Association Kalisher Lecture as “a novel way of implementing an excellent Report”. This paper considers the possible evolution of the common law in light of these amendments, the challenges associated with adopting such a novel approach to reform and the potential opportunities for the improvement of expert evidence in criminal proceedings that the changes were intended to create.