NMC has been all over this, and reports that Jim Hood has obtained a TRO on the basis that some of the pardons may not've complied with Section 124 of the state constitution, which requires 30 days' notice via newspaper publication prior to a pardon's issuing.
Not at all my area of the law, but Justice Ethridge's dissent in State ex rel. Boone v. Metts, 125 Miss. 819 (1921), bears quotation:
For instance, he is limited in granting a pardon to such cases as where publications have been made for thirty days in a newspaper of the county, but his decision as to whether the publication was made is not open to judicial review.Ethridge - one of the more respected justices of his day - makes this statement without citation, as if it were too obvious to need support. I don't see where the majority disagrees.
What kind of limit Section 124 sets, if the governor is himself the judge of whether the limit doesn't apply, is a question I wish I could ask Justice Ethridge; but given the paucity of law on the subject, it seems worth mentioning.