Freedoms under the U.S. Constitution apply differently to different kinds of businesses. For partnerships and sole proprietorships, constitutional freedoms apply individually to their owners and employees, rather than to the business itself. However, some freedoms under the U.S. constitution apply directly to corporations, which are considered artificial persons for this purpose.
The Commerce Clause
All interstate and international business, as well as business with American Indian tribes, is governed by the Commerce Clause (Article 1, Section 8, Clause 3) of the U.S. Constitution. This clause gives Congress the power to regulate commerce which crosses state, reservation, or international lines, although the exact federal limits of power under this clause are a constant court battle.
Most of the debate is about which kinds of interstate commerce are legitimately regulated at the federal level. In general, modern Supreme Court decisions have limited federal powers over interstate commerce to trade and production. During judicial interpretation, the Commerce Clause is usually paired with the Necessary and Proper clause at the end of Article 1, Section 8.
The 14th Amendment: Equal Protection Clause
Under the Equal Protection Clause, corporations are now considered to be artificial persons. Thus, the corporation itself is protected by several of the same constitutional rights as apply to individuals.
The concept of corporate personhood goes back to Santa Clara County v. Southern Pacific R. Co, 118 U.S. 394 (1886), in which the railroad requested the same kind of tax deduction based on mortgage as private individuals were getting. The court granted it. The court reporter’s headnote adds that Chief Justice Morrison Waite made a separate comment before argument:
“The Court does not wish to hear argument on the question whether the provision in the Fourteenth Amendment to the Constitution which forbids a state to deny to any person within its jurisdiction the equal protection of the laws applies to these corporations. We are all of opinion that it does.”
Thus, the concept of corporate personhood was not explicitly stated in the court decision itself. However, it was background to it, but without precedent. Previous decisions had already recognized that corporations were entitled to some of the protections of the U.S. Constitution, but did not state equality or open the door to corporate personhood.
Other constitutional rights which apply to commerce
First Amendment rights which may apply to commerce include freedom of speech, freedom of the press, and freedom of assembly. While governments have the right to tax newspapers and other journalistic media, they cannot do so with an exclusive tax. However, government is allowed to tax different types of media differently.
Religious businesses such as Scientology take advantage of freedom of religion, which is a matter of ongoing legal dispute. Another matter of constant legal dispute is the ability of any level of government to place limits on the Second Amendment right which gives businesses the right to buy and sell firearms.