Go to the Trademark Electronic Search System at the official website of the U.S. Patent and Trademark Office. Use the "Basic Word Mark Search (New User)" search. Enter the phrase into the "Search Term" field; leave the default search options set for a basic search. The default search options are "Combined Word Mark" with "All Search Terms (AND)." These settings will return results containing all the words in the phrase and search word variations. View results to see trademarked phrases.
Widen the search and search again if you're not sure of the exact phrase. Change the "Results Must Contain" search option to "Any Search Terms (OR)." This will return results that contain parts of the phrase you are searching for.
Click the "Logout" button beneath the search fields when finished.
Go to the official website of the United States Copyright Office to use its online "Public Catalog Search" for works copyrighted after 1978. Use the "Keyword" search field for phrases in copyright records. Surround the phrase with double quotation marks to search for the precise phrase.
Check the results for the phrase you want. Results are shown by the title of the works that contain the phrase, and are arranged alphabetically.
Search again using the "Keyword" search if the exact phrase you are looking for doesn't appear in the results. Use some distinctive words from the phrase. For example, if searching, "The brown shoehorn," omit the words "the" and "brown." "Shoehorn" is the less common word. Put a "+" in front of each search word to narrow the search.