At least one U.S. president, Bill Clinton, has used the office's sweeping pardon powers to grant a pardon to a family member. A series of "midnight pardons" by President Clinton during his last hours in office included a pardon of his half-brother Roger Clinton, who had been convicted of a conspiracy to distribute cocaine and distribution of cocaine in 1985.
In a subsequent congressional probe of Clinton administration pardons, Roger Clinton was investigated for allegedly accepting personal gifts in exchange for pardons and diplomatic passports.
In general, there are few clear constitutional limits on the presidential pardon power, aside from an explicit prohibition on presidents using pardons to immunize themselves from impeachment.