Sentencing guideline schemes require courts to sentence within the guidelinesor give reasons why a different sentence is appropriate. Most U.S. schemes require courts to find 'substantial and compelling' grounds for departing from the guidelines. The duty of a court with respect to sentencing guidelines in England and Wales changed significantly in 2010 as a result of the Coroners and Justice Act 2009. This article explores the evolution of the duty of British courts to comply with the English sentencing guidelines. As will be seen in the current study, the language of the duty of a court provision has become more robust: henceforth, courts 'must follow' definitive guidelines rather than merely 'have regard to' them. At the same time, the government significantly increased the range of sentence within which courts must sentence. The essay provides some international context, drawing upon experiences in the jurisdiction in which guidelines have been longest in existence, and explores the limited compliance statistics collected in England and Wales to date. The consequences of the latest changes for sentencing in England and Wales are discussed. (Published Abstract)