WASHINGTON (Reuters) - "Trump Too Small" - a phrase mocking former President Donald Trump that a California lawyer intended to slap on T-shirts - instead has become the center of another U.S. Supreme Court battle exploring the intersection of trademark law and free speech rights. The justices are set to hear arguments on Wednesday in the U.S. Patent and Trademark Office's appeal of a lower court's decision that reversed the agency's denial of attorney Steve Elster's 2018 trademark application for "Trump Too Small." At issue is whether the U.S. Constitution's First Amendment free speech protections for criticism of public figures outweigh the agency's concerns over Trump's rights, as the lower court found.