Via Josh Marshall, comes a story at Breitbart, Former DOJ Attorney: Illegal for Democrats to Vote in MS GOP Primary Runoff. Here’s the relevant part of the article:

J. Christian Adams, a former Civil Rights Division attorney at the Department of Justice with experience litigating election law cases in Mississippi, said a law there prevents people from voting in the primary for candidates they don’t plan to support in the general election….

The Mississippi law Adams cites, MS Code 23-15-575, states: “No person shall be eligible to participate in any primary election unless he intends to support the nominations made in which he participates.”

“Mississippi law prohibits Democrats from voting in a Republican primary,” Adams said in an emailed statement. “Obviously poll workers aren’t mind readers. But if someone doesn’t intend to support the nominee in November, then that person isn’t allowed to vote in the Republican primary.”

In addition, the state Democratic Party sued Gov. Haley Barbour and others in the mid-2000s regarding just that matter—prompting United States District Judge W. Allen Pepper to write in a June 8, 2007, opinion that it is the responsibility and right of the political party holding a primary election to ensure that the elections are fair and legal. In the case of a Republican primary and runoff, only Republicans vote, and in the case of a Democrat primary and runoff, only Democrats vote—and it is the role of the political parties to ensure that process is handled correctly.

The Supreme Court determined in a 2005 case that the First Amendment “protects the right of political parties to associate with fellow members and disassociate with non-members,” Judge Pepper wrote in his opinion. So technically it’s the party’s responsibility—i.e., in this case, state GOP chairman Joe Nosef’s responsibility—to protect GOP voters’ First Amendment rights by working to keep Democrats from voting in the GOP primary runoff.