The U.S. Constitution defines treason as: "Treason against the United States, shall consist only in levying war against them, or in adhering to their enemies, giving them aid and comfort." (Article III, Section 3)
The legislature of South Carolina displays the battle flag of the Army of Northern Virginia on its grounds, an illegal militia whose sole purpose was, "levying war against [the United States]". In so doing, they declare themselves to be either in the process of, "levying war against [the United States]," or, "adhering to their enemies, giving them aid and comfort."
We cannot have the legislature of one of our fifty states declaring themselves to be in active war against the United States. They need to be investigated for this treason.