This is the first in a series of three articles undertaking an in-depth study of Canadian judicial review and appeal decisions decided in English post-Dunsmuir. This article sets out the foundations of our research based on a set of 104 questions, focusing on both choice and application of standard of review and, applying that analytical structure, examines federal court decisions made between 2008 and 2015. We ask how those decisions reflect the key changes introduced by Dunsmuir, including: (a) the move to one deferential standard; (b) an analytical focus on applying rather than selecting the standard of review; (c) a description of reasonable decisions as ones where the reasoning is transparent, justifiable and intelligible, and the result falls within a reasonable range of outcomes, taking account of the law and the facts; and (d) a renewed emphasis on the centrality of deference.