Section 41 of the Official Languages Act is a critical component of Canada’s language rights architecture but remains poorly understood from a legal perspective. This article explores in detail the nature and structure of s. 41 as a legal norm. The discussion is divided into three parts. Part I conducts a conceptual analysis based solely on the text of s. 41, in order to canvass more systematically than has been done to date the range of interpretive possibilities offered by that provision. To that end, I first consider whether s. 41(2) should be viewed as creating a “right”, properly speaking, or rather some other form of duty, and what consequences this might have for its substantive content. Next, I explore in some detail the structure of that duty—or rather, the competing theories as to how that structure should be defined, which I label the Holistic Thesis and the Casuistic Thesis. Part II then sets out to resolve this fundamental ambiguity, and argues that the Casuistic Thesis ought to be preferred. I begin with a detailed analysis of the legislative history of the 2005 amendments to s. 41, which demonstrates that the Casuistic Thesis offers by far the best account of Parliament’s intent in adopting those changes. I then briefly consider the specialized interpretive principles applicable to language rights measures, which also support this conclusion. Finally, in Part III, I offer a case study of the Casuistic Thesis in practice by analysing a relatively recent Federal Court decision involving Statistics Canada, which I argue was wrongly decided.