Circuit Judge Tomie Green issued an injunction late Wednesday at the request of Democratic Attorney General Jim Hood.
Hood said he believes Barbour might've violated the state constitution by pardoning some inmates who failed to give sufficient public notice that they were seeking to have their records cleared.
Barbour said in a statement Wednesday, a day after leaving office, that he believes people have misunderstood why he gave reprieves to more than 200 inmates. Most received full pardons, while others received suspended sentences because of medical conditions. Barbour said 189 of the inmates had already completed their incarceration.
Barbour was limited to two terms and issued the list of pardons and early releases Tuesday about the time his successor, Republican Phil Bryant, was being inaugurated. Barbour wouldn't answer repeated questions about the pardons Tuesday.
In Wednesday's statement, Barbour said: "The pardons were intended to allow them to find gainful employment or acquire professional licenses as well as hunt and vote. My decision about clemency was based upon the recommendation of the Parole Board in more than 90 percent of the cases."
The pardons angered even some of Barbour's most ardent supporters in Mississippi, including some conservatives who say the actions tarnished his legacy. It also has created concerns within the state that his decisions may make Mississippi look backwards. Yet Barbour is unlikely to face political repercussions from the decisions — he has said he doesn't expect to run for any elected office, nor does he expect to be chosen as a GOP vice-presidential nominee.
Barbour spokeswoman Laura Hipp was not immediately available for comment about Green's decision to temporarily block release of the 21 inmates. It was not clear how many of the 21 are convicted killers.
Section 124 of the Mississippi Constitution says any inmate seeking a pardon must publish notice about his intentions. Before the governor can grant it, the notice must appear 30 days in a newspaper in or near the county where the person was convicted.
Hood said it's not clear whether all the inmates pardoned by Barbour met the publication requirement, and that he believes it's likely that some did not.
"It's unfortunate Gov. Barbour didn't read the constitution," Hood said Wednesday.
Mississippi Department of Corrections spokeswoman Suzanne Singletary told The Associated Press that five inmates let out over the weekend are the only ones on Barbour's list who had been released as of Wednesday evening. She said the 21 were still in custody because processing paperwork generally takes several days. Among other, things, state law requires the department to give victims 48 hours' notice before an inmate is released.
Neither Hipp nor Barbour's lead staff attorney, Amanda Jones Tollison, responded to questions about whether Barbour's staff verified that pardoned inmates had met the 30 days' publication requirement.
Each of the five inmates released this past weekend had worked as a trustee at the Governor's Mansion. They are David Gatlin, convicted of killing his estranged wife in 1993; Joseph Ozment, convicted in 1994 of killing a man during a robbery; Anthony McCray, convicted in 2001 of killing his wife; Charles Hooker, sentenced to life in 1992 for murder; and Nathan Kern, sentenced to life in 1982 for burglary after at least two prior convictions.
Singletary said each of the five men published legal notices in local newspapers within the past month.
Hood said several of his staff members spent hours Wednesday calling newspapers and checking whether others on the clemency list published their notices in advance. He said Green agreed to his request to require each of the five who've been released to appear in court to prove they met the publication requirement. He did not say where or when those appearances would take place.
Relatives of the killers' victims said they were outraged by the release, and some said they're worried for their own safety.
Barbour, a former Republican National Committee chairman, considered running for president this year but announced last April that he would skip the race because he didn't have the "fire in the belly." The 64-year-old is now on the paid speakers' circuit and is also working for a Jackson-area law firm and for BGR, the Washington lobbying firm he founded two decades ago.
Associated Press writer Jeff Amy contributed to this report.