Could Joe Arpaio Break the Presidential Pardon?
"...the controversial sheriff of Maricopa County, Arizona—convicted of criminal contempt of court—has decided to try to clear his name, asking a court to vacate his original conviction entirely. (Normally, a pardon protects the pardoned person from punishment, but leaves the fact of the conviction on the books.) Arpaio might indeed get his record wiped clean. But in asking a court to vacate his conviction, Arpaio is inviting another possibility as well: that the court will decide his pardon was not valid in the first place. If that happens, the pardon would mark a new development in the law: judicial willingness to limit the presidential pardon power itself."

http://www.politico.com/magazine/story/2017/10/04/trump-arpaio-break-pardon-215676