From the Document: "This report provides an overview of the President's pardon power. After briefly discussing the historical background to the power conferred by Article II, Section 2 of the Constitution, the report explores the different forms of clemency that are available, the relatively few limits on the pardon power, and the process of seeking and receiving clemency. The report concludes by addressing selected legal issues related to the pardon power: (1) the legal effect of pardons and other forms of clemency; (2) whether the President may grant clemency to himself; and (3) Congress's role in overseeing the use of the pardon power."
CRS Report for Congress, R46179
Congressional Research Service: https://crsreports.congress.gov/