Question: If one has been using a name as a common law trademark, what is involved in challenging a trademark approved to someone else?
I and some friends have been using a name for a science fiction universe since 1996. The name was used for a group of fighters set in the future. We went public with it in February 2009, in which we posted chapters, art, etc., on a website and distributed flyers to publicize. We have plans to publish books and other media, such as games (we've come up with game ideas and have written about it). I found out this year that a game came out about a group of fighters set in the future with a similar art style for the characters and using the same name we use for the game. We understand that we were using the name as a common law trademark. The game company filed the trademark in October 2009 and later got approval. What is involved in challenging it?
Answer: To challenge the trademark registration of the other company based on your prior use and present confusion between the two marks, you could initiate a cancellation proceeding in the trademark office – http://www.uspto.gov/trademarks/process/appeal/tbmp_3rd_ed_rev_1_chapter_300.pdf
Another mechanism would be to file a lawsuit in federal court.