USPTO states that their trademark database is NOT a superset of the state-level registrations and common law marks: http://tess2.uspto.gov/ http://tess2.uspto.g

USPTO states that their trademark database is NOT a superset of the state-level registrations and common law marks: http://tess2.uspto.gov/ http://tess2.uspto.gov/ At the least, you also need to check each of the 50 state-level PTDLs. USPTO has a list by state: http://www.uspto.gov/products/library/ptdl/locations/index.jsp http://www.uspto.gov/products/library/ptdl/locations/index.j... The other theoretical benefit of a professional search is that they are expected to research similar marks as well, taking advantage of their legal expertise to determine how similar is too similar. (I emphasize 'theoretical'.)