Inspired by the work of Professor Michael Taggart, this collection of essays from across the common law world is concerned with two separate but related themes. First, to what extent and by what means should review on substantive grounds, such as unreasonableness, be expanded and intensified? Jowell, Elliott, and Varuhas all agree with Taggart that proportionality should not 'sweep the rainbow, ' but propose different schemes for organizing and conceptualizing substantive review. Groves and Weeks, and Hoexter evaluate the state of substantive review in Australia and South Africa respectively....