They did pass a law, Rich. It's in the statutes. "E-cigarettes" and "vapor products" have been deemed by the South Dakota state legislature to be "tobacco products."
34-46-20. Tobacco product includes vapor product. For the purposes of §§ 34-46-2 to 34-46-6, inclusive, and 34-46-21, the term, tobacco product, includes vapor product. The term, vapor product, means any noncombustible product containing nicotine that employs a heating element, power source, electronic circuit, or other electronic, chemical, or mechanical means, regardless of shape or size, that can be used to produce vapor from nicotine in a solution or other form. The term, vapor product, includes any electronic cigarette, electronic cigar, electronic cigarillo, electronic pipe, or similar product or device and any vapor cartridge or other container of nicotine in a solution or other form that is intended to be used with or in an electronic cigarette, electronic cigar, electronic cigarillo, electronic pipe, or similar product or device. The term, vapor product, does not include any product approved by the United States Food and Drug Administration for sale as tobacco cessation products and marketed and sold solely for that purpose.
Source: SL 2014, ch 173, § 1.
Covers just about everything the FDA covered. I think they copied their paper.