This response to Professor Motomura considers what is lost through the elaboration of formally defined boundaries around prosecutorial discretion. Professor Motomura and others in this Issue rightly extol the many benefits of the President's November 2014 executive actions. While I share the view that those benefits are considerable, I believe a full accounting requires us to consider what gets lost in this process, including identification of the immigrants in the limbo space between the actions' prospective beneficiaries at the one end and those who are priorities for removal on the other. This Essay focuses on the cost that comes from the loss of a different kind of discretion in immigration law, where discretionary authority can act as a corrective measure at the edges of rules, where defined edges bump up against immigrants in limbo.

Discretion is always an elusive concept: "interstitial," and like the hole in a doughnut, as Professor Dan Kanstroom has written-defined more by what is around it than by the space itself. The less defined the edges of that space are, the more that space is full of possibility. The malleability of this space generally cuts against the values of transparency and accountability that are rightly lauded by many of the scholars in this symposium Issue. Individualized discretion, guided generally by policy interests and preferences, and not subject to carefully drawn limits and clearly defined edges, is indeed anathema to those values-and yet it serves an important purpose. The discretion available at the law's margins constitutes a vital means to correct the errors that inevitably happen at the law's edges, where even the best rules do an imperfect job of capturing the world's complexity. This kind of remedial, equitable discretion is a kind of discretion that has been steadily whittled down over the past twenty-five years in immigration law.