[Excerpt] This report begins by discussing the sources of federal power to regulate immigration and, particularly, the allocation of power between Congress and the President in this area. It next addresses the constitutional and other foundations for the doctrine of prosecutorial discretion, as well as the potential ways in which prosecutorial discretion may be exercised in the immigration context. It concludes by addressing potential constitutional, statutory, and administrative constraints upon the exercise of prosecutorial discretion. The report does not address other aspects of discretion in immigration law, such as the discretion exercised by immigration officers in granting benefits (e.g., asylum), or by immigration judges in non-enforcement contexts (e.g., cancellation of removal).