Montana Gov. Greg Gianforte on Wednesday signed into law a first-of-its kind bill that makes it illegal for TikTok to operate in the state. The law would have much more far-reaching effects than bans already in place in nearly half the states and the U.S. federal government that prohibit use of the app on government devices. The new rules are expected to face legal challenges. And experts say it will be extremely difficult to enforce, if not impossible.