U.S. Constitution, Article I, Section 8, clauses 3, 8, and 18
The Congress shall have power . . .
. . . .
 To regulate commerce with foreign nations, and among the several states, and with the Indian tribes;
. . . .
 To promote the progress of science and useful arts, by securing for limited times to authors and inventors the exclusive right to their respective writings and discoveries;
. . . .
 To make all laws which shall be necessary and proper for carrying into execution the foregoing powers, and all other powers vested by this Constitution in the government of the United States, or in any department or officer thereof.
15 U.S.C. § 1052. Trademarks Registrable on the Principal Register; Concurrent Registration
No trademark by which the goods of the applicant may be distinguished from the goods of others shall be refused registration on the principal register on account of its nature unless it—
(a) Consists of or comprises immoral, deceptive, or scandalous matter; or matter which may disparage or falsely suggest a connection with persons, living or dead, institutions, beliefs, or national symbols, or bring them into contempt, or disrepute; or a geographical indication which, when used on or in connection with wines or spirits, identifies a place other than the origin of the goods and is first used on or in connection with wines or spirits by the applicant on or after one year after [the effective date of the WTO agreement].
(b) Consists of or comprises the flag or coat of arms or other insignia of the United States, or of any State or municipality, or of any foreign nation, or any simulation thereof.
(c) Consists of or comprises a name, portrait, or signature identifying a particular living individual except by his written consent, or the name, signature, or portrait of a deceased President of the United States during the life of his widow, if any, except by the written consent of the widow.
(d) Consists of or comprises a mark which so resembles a mark registered in the Patent and Trademark Office, or a mark or trade name previously used in the United States by another and not abandoned, as to be likely, when used on or in connection with the goods of the applicant, to cause confusion, or to cause mistake, or to deceive . . . .
(e) Consists of a mark which (1) when used on or in connection with the goods of the applicant is merely descriptive . . . of them [subsections (e)(2) through (e)(5) omitted].
(f) Except as expressly excluded in subsections (a), (b), (c), (d), (e)(3), and (e)(5) of this section, nothing herein shall prevent the registration of a mark used by the applicant which has become distinctive of the applicant’s goods in commerce [i.e., attained “secondary meaning” as described in the note preceding the Qualitex case]. . . .
15 U.S.C. § 1114. Remedies; infringement; innocent infringement by printers and publishers
(1) Any person who shall, without the consent of the registrant—
(a) use in commerce any reproduction, counterfeit, copy, or colorable imitation of a registered mark in connection with the sale, offering for sale, distribution, or advertising of any goods or services on or in connection with which such use is likely to cause confusion, or to cause mistake, or to deceive; or
(b) reproduce, counterfeit, copy, or colorably imitate a registered mark and apply such reproduction, counterfeit, copy, or colorable imitation to labels, signs, prints, packages, wrappers, receptacles or advertisements intended to be used in commerce upon or in connection with the sale, offering for sale, distribution, or advertising of goods or services on or in connection with which such use is likely to cause confusion, or to cause mistake, or to deceive,
shall be liable in a civil action by the registrant for the remedies hereinafter provided. . . .
15 U.S.C. § 1125. False designations of origin, false descriptions, and dilution forbidden
(a) Civil action
(1) Any person who, on or in connection with any goods or services, or any container for goods, uses in commerce any word, term, name, symbol, or device, or any combination thereof, or any false designation of origin, false or misleading description of fact, or false or misleading representation of fact, which—
(A) is likely to cause confusion, or to cause mistake, or to deceive as to the affiliation, connection, or association of such person with another person, or as to the origin, sponsorship, or approval of his or her goods, services, or commercial activities by another person, or
(B) in commercial advertising or promotion, misrepresents the nature, characteristics, qualities, or geographic origin of his or her or another person’s goods, services, or commercial activities,
shall be liable in a civil action by any person who believes that he or she is or is likely to be damaged by such act.
15 U.S.C. § 1127. Construction and definitions; intent of chapter [selections]
The term “trademark” includes any word, name, symbol, or device, or any combination thereof—
(1) used by a person, or
(2) which a person has a bona fide intention to use in commerce and applies to register on the principal register established by this chapter,
to identify and distinguish his or her goods, including a unique product, from those manufactured or sold by others and to indicate the source of the goods, even if that source is unknown.
[other portions omitted]