Fast food chains battle over 'Taco Tuesday' trademark.

Taco Bell has filed a petition with the US Patent and Trademark Office to cancel Taco John's trademark of "Taco Tuesday," claiming that the phrase is too common and widely used to be exclusively owned by one company. Taco John's, a Wyoming-based fast-food chain, has been using the trademark since the 1980s and has actively enforced it, sending letters to other businesses that use the phrase. Taco Bell, which has more than 7,200 locations worldwide, is asking for the trademark to be canceled in 49 states and is also contesting a New Jersey restaurant's claim to the phrase.