Blackburn also took part in a number of prominent legal challenges of major constitutional significance, including R v Commissioner of Metropolitan Police, ex parte Blackburn,[REF][REF] on illegal gambling and the duties of the police, and Blackburn v Attorney-General,[REF] on the constitutionality of the European Communities Act 1972.
In 1972, he decided to pursue this matter into the Court of Appeal, which confirmed the 1968 judgment, in a separate matter of enforcement against the British Board of Film Censors and a cinema[REF] of the pornography laws then extant.