South Carolina's open primary electoral system (not to be confused with the nonpartisan top-two primary in California and Washington) is looking much safer following the withdrawal of the State Republican Party from an anti-open primary lawsuit. They have been challenging South Carolina's nonpartisan open primary election process since 2010 and have been unsuccessful in numerous attempts.
Among other arguments, the open primary defendants argued against requiring voters to claim party affiliation in order to participate in the State's primary election.
In a statement, Jackie Salit, President of Independentvoting.org said,
“We’re glad to see the State Republican Party come to its senses, Locking out independent voters to control nominations sends the wrong message. I invite the State GOP to now join our coalition of interveners which is asking the Court to lay this reactionary boondoggle to rest."
Independentvoting.org is an intervenor in the suit along with the the Progressive Network and South Carolina's Legislative Black Caucus. Several minor parties are intervenors as well, including the Columbia Tea Party, the Constitution Party, and South Carolina's Independence Party.
Challenges to the constitutionality of nonpartisan open primaries were struck down in a South Carolina court in 2011, however evidence will be heard once the case goes to trial on August 21st.