Earlier this week, the Disney+ twitter handle tweeted that if people tweeted the phrase “May the 4th be with you” (in reference to the Star Wars phrase “May the force be with you”), then the user would be subject to a terms of service agreement. Many people ended up replying to the tweet thread. Some were making fun of what Disney+ is trying to do, and others were saying that is not how trademark law and contract law works.
Disney does not have the unilateral power to bind people to a terms of service agreement just for using a phrase. Simply using a phrase should not force you into a legally binding contract, let alone with a service that someone has not specifically agreed to. That would be similar to being legally bound to a contract solely for saying a slogan out loud.
Trademark law protects certain words, symbols, phrases, and more which identifies products and/or services from a particular source. Disney does own the trademark for “May the fourth be with you”, for shirts, tops, stickers, (for products) and live entertainment services after its acquisition of LucasFilms. However, using the phrase alone does not mean that someone is infringing on the trademark. As long as someone is not using the phrase in connection with certain products or services, they should be ok. You can still say the phrase, but don’t go making your own t-shirts or live performances using it.
Disney+ did say that there is something special planned, but my opinion is that they should reach out to certain people and ask if Disney can use the person’s tweets in whatever it is that is being planned.