South Carolina requires "subversives" to register with the government

Seriously:

Terrorists who want to overthrow the United States government must now register with South Carolina's Secretary of State and declare their intentions -- or face a $25,000 fine and up to 10 years in prison.

The state's "Subversive Activities Registration Act," passed last year and now officially on the books, states that "every member of a subversive organization, or an organization subject to foreign control, every foreign agent and every person who advocates, teaches, advises or practices the duty, necessity or propriety of controlling, conducting, seizing or overthrowing the government of the United States ... shall register with the Secretary of State."

There's even a $5 filing fee.

By "subversive organization," the law means "every corporation, society, association, camp, group, bund, political party, assembly, body or organization, composed of two or more persons, which directly or indirectly advocates, advises, teaches or practices the duty, necessity or propriety of controlling, conducting, seizing or overthrowing the government of the United States [or] of this State."

From Raw Story, via skidder in this iTulip thread. The curious thing is, they don't define "overthrowing" the government in the statute, which is a little worrisome to say the least. Obviously advocating violence to change the system would qualify, but what else? Would advocating substantial reform of the system (proportional representation, abolition of the Electoral College, etc) count? Would campaigning to defeat an incumbent governor count? Who decides such matters?