Pre-emptive pardons are a distinct possibility now that current and former Trump advisers are under Mueller’s scrutiny. Trump himself has tweeted that everyone agrees the U.S. president has “complete power to pardon." Some of those kinds of executive moves have been well studied, including Gerald Ford’s swift pardon of Richard Nixon and Bill Clinton’s exoneration of fugitive financier Marc Rich. But the legal territory is largely uncharted over pardons of a president’s own campaign workers, family members or even himself -- and how prosecutors’ work would then be affected.