The 12th Edition covers: the classification of primary, subordinate and a growing range of quasi-legislation; the potential of and constraints on all kinds of legislation, including devolved legislation; the legislative process for all kinds of legislation; drafting of different kinds of legislation; explanatory material (including Explanatory Notes and Pepper v Hart); issues of effect from timing and application, the exercise of statutory functions, statutory corporations, effect on other law and errors in legislation (including an account of increasing judicial activism in rectification); the rules, presumptions and canons and principles of statutory interpretation; and a discussion of the effects of EU legislation in UK law.

All recent developments are covered in the 12th Edition including discussion of the developing relationship between legislation and the prerogative, Parliament and the Executive (including Miller 1 and 2 - the Brexit cases), discussion of the latest judicial attitudes to the relationship between legislation and the common law (including the recent Tate Gallery decision on nuisance), and hundreds of other recent cases and political developments (including an account of fundamental changes to legislation in Wales).

The 12th edition, published in November 2020, is now supplied as a set inclusive of the 2nd Cumulative Supplement published in October 2022. The 2nd supplement provides coverage of new developments across the whole range of core legislation issues, including breadth of powers, strict liability in crime, role of quasi-legislation, anticipatory and retrospective legislation, breadth of Ministerial powers, and presumptions of construction