I am an election commissioner and when we had our FIRST closed primary this spring, it was chaos. People kept saying"How can I be a Democrat, I've voted Republican for YEARS!"
Elections in Louisiana, with the exception of U.S. presidential elections (and congressional races beginning in 2008), follow a variation of the open primary system called the jungle primary. Candidates of any and all parties are listed on one ballot; voters need not limit themselves to the candidates of one party. Unless one candidate takes more than 50% of the vote in the first round, a run-off election is then held between the top two candidates, who may in fact be members of the same party.