The First Amendment to the United States Constitution provides that Congress shall make no law abridging (curtailing) the freedom of speech. Thus, free speech is only protected by the U.S. Constitution when it is the government that seeks to limit free speech. The First Amendment is inapplicable when a nongovernmental person or entity—such as a private business—seeks to limit free speech.

And some types of speech are afforded more protection than others. For example, commercial speech—speech that proposes a commercial transaction—is entitled to First Amendment protection, but less protection than political speech.

In the 1980 case Central Hudson Gas & Electric Corp. v. Public Service Commission, the U.S. Supreme Court developed a four-part test to determine whether commercial speech regulation violates the First Amendment:

1. Whether the commercial speech concerns a lawful activity and is not misleading;

2. Whether the government interest asserted to justify the regulation is "substantial";

3. Whether the regulation "directly advances" that government interest;

4. Whether the regulation is no more extensive than necessary to serve that interest.

In New York, as in the rest of the United States, the First Amendment protects freedom of speech from government infringement but does not apply to private entities. This means that while the government cannot unduly restrict speech, private businesses and individuals are not bound by the First Amendment to uphold the same standards of free speech. However, when it comes to commercial speech, which includes advertising and other speech proposing a commercial transaction, there is still some level of First Amendment protection, albeit less than that afforded to political speech. The Central Hudson Gas & Electric Corp. v. Public Service Commission case established a four-part test to assess the constitutionality of commercial speech regulation. This test is used to ensure that any government regulation of commercial speech is justified by a substantial interest, directly advances that interest, and is not more extensive than necessary. Attorneys in New York advising on matters of commercial speech must consider this test when determining the legality of government regulations affecting such speech.