Both houses of the South Carolina legislature have now passed bills that make it more difficult for independent candidates to get on the ballot. However, the versions in each house are significantly different.
The House bill, HB 3746, is worse. It does not reduce the number of signatures, and it imposes three crippling restrictions: (1) no one could sign who had voted in the primary, or who will vote in a future primary that year; (2) newly-registered voters could not sign; (3) no one could sign for two independent candidates running for the same office.
The Senate bill, SB 590, is the same as the House bill, except it at least reduces the number of signatures. Statewide and U.S. House petitions would go from 10,000 signatures to 4,000 signatures; legislative candidates would go from 5% of the number of registered voters, to 3%. The Senate bill passed the Senate on February 3.
The part of the bills that says newly-registered voters cannot sign would be unconstitutional, under a U.S. Supreme Court summary affirmance from 1970, Socialist Workers Party v Rockefeller. The primary screenout would almost surely be unconstitutional if the number of signatures is not reduced. Even with no primary screenout, no independent candidate for either house of Congress has ever qualified for a government-printed ballot in South Carolina. In Storer v Brown, the U.S. Supreme Court said that a 5% (of the last vote cast) petition, combined with a primary screenout, is probably unconstitutional, and the way to settle the matter is to see how often any candidate has been able to get on the ballot.