How did they decide this? They're not glad you asked. But since you're curious, for it to be considered clothes, the court says it'd need "closures." For it to actually be clothes, "At a minimum, one must wear the Snuggie backwards." Judge Mark Barnett of the Court of International Trade said they can be used just like a blanket. It could be used "in the types of situations one might use a blanket; for example, while seated or reclining on a couch or bed, or outside cheering a sports team."
It's actually a big win for the makers of Snuggie (and presumably Slanket, if that's still a thing). The maker, Allstar Marketing Group, has been at odds with the U.S. Department of Justice since 2010. The ruling means they'll only pay an 8.5 percent tariff to import the
lazy-day robe blankets. As an article of clothing, they would pay a 14.9 percent tax rate because of how the product is categorized.