This is just for reference and not a concession that the current residents of the White House have any standards:
“In general, a pardon is granted on the basis of the petitioner’s demonstrated good conduct for a substantial period of time after conviction and service of sentence. The Department’s regulations require a petitioner to wait a period of at least five years after conviction or release from confinement (whichever is later) before filing a pardon application (28 C.F.R. Â§ 1.2). In determining whether a particular petitioner should be recommended for a pardon, the following are the principal factors taken into account.”
- Post-conviction conduct, character, and reputation.
- Seriousness and relative recentness of the offense.
- Acceptance of responsibility, remorse, and atonement.
- Need for relief.
- Official recommendations and reports.
Of course, the President can decline to take these factors into account and grant a pardon for any reason he chooses. Including to insure the loyalty and continued silence of a former staffer who knows where the bodies are buried.