A Trademark gives you the right to prevent others from using your registered mark as an indicia of source on their goods or services. So, only Nike can use the word “Nike” to sell shoes and athletic apparel. Only Delta Airlines can use the word “Delta” with regards to airlines or air travel. However, Delta Faucets has peacefully coexisted with Delta Airlines for decades because no consumer really thinks they’re buying air travel from a faucet and sink maker, thus there is no reasonable “likelihood of confusion” that could lead to the consumer being harmed by that purchase.
Southwest Airlines is the only airlines that can use the word “Southwest” as an indicia of source, but they cannot prevent other airlines from saying that they fly routes within the Southwestern United States, because that would unreasonably limit competition. The law specifically prohibits that sort of monopoly on language. So, owning a trademark doesn’t mean other people can’t use the word or words, it means that others can’t use it in a trademark capacity- meaning, they can’t use it to indicate the source of goods or services in commerce.
Jessica Alba’s The Honest Company may have a trademark, but they cannot prevent others from describing another company as “honest.” That may seem like common sense but sometimes a company that has trademarked a name or phrase wants to prevent anyone else from using that name or phrase. Trademark law is written to specifically avoid giving this kind of monopoly over language to Trademark holders. Unless they are using your mark to indicate a source of goods or services in commerce, in a close enough industry to yours, then it’s unlikely you have the right to prevent them from using that language. Not sure? Consult with a Trademark attorney.
A trademark registered in the US only has jurisdiction in the US and doesn't protect you internationally. You can, however, use your trademark to register with Customs and Border Protection so they can police for counterfeit goods bearing your mark, or goods bearing your mark that are not supposed to be sold into certain regions. You can also use your US registration as a basis for registration in other countries that are signatories to the Madrid Protocol, an international treaty related to IP protection. We will address those in later posts.