Pardons apply to known crimes, unknown crimes, past crimes, crimes that have not yet been prosecuted. Only crimes that have not yet been committed are not eligible for Presidential parson. See Ex parte Garland, 71 U.S. (4 Wall.) 333 (1866)
A Presidential pardon "extends to every offence known to the law, and may be exercised at any time after its commission, either before legal proceedings are taken, or during their pendency, or after conviction and judgment."
They cannot. It is not possible to pardon someone for a crime that has yet to be committed. Unknown crimes, of course. Unprosecuted crimes, yes. Crimes for which a conviction has been obtained? Or course. Pre-crime pardon? No.
I was simply stating the pardon power is absolute but does not apply to "future crimes." And I agree that it does not exist if the President is illegitimate. Even if Obama pardoned himself, it wouldn't be worth a shit because he was never eligible to be President in the first place. Nothing he did is legitimate.