While emblazoning a logo on the front of a t-shirt or hoodie does not preclude the logo from functioning as a source identifier in the minds of the consuming public, it could lead to the conclusion that the emblazoned logo is mere ornamentation that does not function as a trademark mark. 

There is no per se rule regarding registerability based on the size of a mark on clothing. In re Lululemon Athletica Can. Inc., Ser. No. 77455710, 2013 TTAB LEXIS 2, at *9 (TTAB 2013); In re Right-On Co. Ltd., Ser. No. 79014936, 2008 TTAB LEXIS 17, at *13 (TTAB 2008). Rather, it is the size, location and dominance of the marks that appear on the clothing that is considered in determining their commercial impression. Lululemon, 2013 TTAB LEXIS 2, at *6. This may come into play in trademark prosecution with respect to the submission of a specimen to show use of a trademark. 

If mark is the only design element on the goods and wholly defines the appearance of the goods or forms the essence of the expressive element for the goods, then that may show a merely ornamental use of the mark rather than a trademark use. See, e.g., Peace Love World Live, 2018 TTAB LEXIS 220, at *9 (finding the proposed mark to be ornamental as applied to a bracelet because, inter alia, it composed the whole of the bracelet's appearance); In re Pro-Line Corp., Ser. No. 74174721, 1993 TTAB LEXIS 24, at *4-5 (TTAB 1993) (finding the proposed mark to be primarily ornamental where its “prominent display immediately catches the eye” and formed “part of the thematic whole of the ornamentation of applicant's shirts”). 

Marketplace evidence also may be considered in determining whether the relevant goods commonly feature decorative elements or that the design featured in the proposed mark is a mere refinement of a common form of ornamentation. Lululemon, 2013 TTAB LEXIS 2, at *3; see also In re Soccer Sport Supply Co., 507 F.2d 1400, 1402 (CCPA 1975) (“[A] design which is a mere refinement of a commonly-adopted and well-known form of ornamentation for a class of goods would presumably be viewed by the public as a dress or ornamentation for the goods.”); In re Gen. Tire & Rubber Co., 404 F.2d 1396, 1398 (CCPA 1969) (affirming mere ornamentation refusal after finding that tire whitewall ornamentation is a common practice in the tire industry and that the proposed mark, a three-ring whitewall design, was a mere refinement of this common practice). For example, such marketplace evidence may include photos showing that similar designs commonly appear in a large size on the front portions of shirts, sweatshirts, and other articles of clothing, which could support the general proposition that clothing commonly features prominently displayed ornamentation or design elements. See In re Eagle Crest, Inc., Ser. No. 77114518, 2010 TTAB LEXIS 346, at *9 (TTAB 2010) (“It is clear that clothing imprinted with this slogan [in the proposed mark] will be purchased by consumers for the message it conveys.”). Thus, consumers may be predisposed to perceiving such elements as something other than indicators of source on such goods and may purchase the goods because of their appearance rather than because they come from a particular source.

Nonetheless, even apparent ornamental designs could be recognized as trademarks, or as including trademarks, because of the relevant mark owner's nonornamental use of the relevant matter on other goods or services. See, e.g., Pro-Line, 1993 TTAB LEXIS 24, at *3 (“The ‘ornamentation' of a T-shirt can be of a special nature which inherently tells the purchasing public the source of the T-shirt, not the source of manufacture but the secondary source. Thus, the name ‘New York University' and an illustration of the Hall of Fame, albeit it will serve as ornamentation on a T-shirt will also advise the purchaser that the university is the secondary source of that shirt.”).

“To show that a proposed mark that is used on the goods in a decorative or ornamental manner also serves a source-indicating function, the applicant may submit evidence that the proposed mark would be recognized as a mark through its use with goods or services other than those being refused as ornamental. To show secondary source, the applicant may show: (1) ownership of a U.S. registration on the Principal Register of the same mark for other goods or services based on use in commerce under §1 of the Trademark Act; (2) ownership of a U.S. registration on the Principal Register of the same mark for other goods or services based on a foreign registration under §44(e) or §66(a) of the Trademark Act for which an affidavit or declaration of use in commerce under §8 or §71 has been accepted; (3) nonornamental use of the mark in commerce on other goods or services; or (4) ownership of a pending use-based application for the same mark, used in a non-ornamental manner, for other goods or services.” TMEP § 1202.03(c). 

So beware, the larger the logo emblazoned on a shirt, the more likely it will be deemed a merely ornamental use of the logo rather than a trademark use.