Changing the law on change in the law: Part 1

• A change in the common law can cast doubt on a past conviction, but the Court of Appeal’s ‘substantial injustice’ test may prevent an appeal from being heard.
• The author traces the conflict between that test and the Criminal Cases Review Commission’s statutory powers.

The Law Commission in its consultation paper on criminal appeals (Consultation Paper 268, 2025, Chapter 10) rightly invited comments on the impact of developments in the common law on past convictions. The issue raises difficult and important questions of criminal law and public policy, but it also prompts some personal reflections and reminiscences concerning the present state of the law.

Fundamental tension

The unusual story that unfolds involves a clash of principles, of institutions, and of courts and reveals a disturbing irregularity in judicial proceedings. At the root of the problem is the tension between two fundamental principles of our legal