The Equal Protection Clause of the 14th Amendment is NOT the basis for selective incorporation of the Bill of Rights.
Those rights which ARE made applicable to the states are considered to be selectively incorporated into the meaning of the word “liberty” in the Due Process Clause of the same amendment.
A mild digression while I explain how this came about:
The US Supreme Court (hereafter USSC) ruled very early that the Bill of Rights (amendments 1-10) did not apply to the states; specifically, that they did not prohibit state actions (Barron v. The Mayor and City Council of Baltimore, 32 U.S. (7 Pet.) 243 (1833)). This is undoubtedly correct as to the First Amendment, as can be seen from the very wording of the amendment (“Congress shall not abridge…”), and was historically correct as to the others (I leave the exercise of confirming this to the reader; in general, read the Constitution and understand its plan). Until the ratification of the 14th Amendment 7/9/1868, there was no check on state action regarding individual rights in the Constitution.
Shortly after the passage of the Fourteenth Amendment, various claims were made asserting that the language of either the Privileges and Immunities clause or the Due Process clause found in Section 1 should be construed to totally incorporate the rights found in the first 8 amendments (amendments 9 and 10 don’t involve individual rights). In the Slaughter-House Cases, 83 U.S. (16 Wall.) 36 (1873), the USSC refused to construe the P & I clause to incorporate those rights, preferring to read that clause as guaranteeing only those rights peculiar to citizens of the United States, as opposed to citizens of the various states within the U.S. (e.g., the right to petition Congress, the right of interstate travel, etc.). As to the Due Process clause, a different approach was taken by the USSC. Instead of incorporating rights from the earlier amendments, the court started striking down state legislation that violated a person’s interest in “liberty.” This interpretation of “substantive due process” by the court was used repeatedly for sixty years to reject attempts by the state to legislate areas of economic importance, on the theory that the legislation arbitrarily violated the due process rights of the people. For example, the state of New York was prevented from enforcing legislation that limited the number of hours bakers could work during a week or a day (60 and 10!) on the theory that it was an arbitrary and unnecessary interference with the “liberty” of employers and employees to enter into contracts (Lochner v. New York, 198 U. S. 45 (1905)). As the court established in Allgeyer v. Louisiana, 165 U.S. 578 )(1897), the “liberty” protected by the 14th Amendment was a more extensive right than the freedom of a person to be able to go where he pleased.
Substantive due process was used liberally from 1896 to 1937 to strike down a variety of laws that regulated economic activity. It substituted the court’s own opinions about the needs of the people for the determinations of the legislatures of the various states. But, it also was used to uphold individual rights, as when Nebraska was prevented from prohibiting the teaching of foreign languages in private schools (Meyer v. Nebraska, 262 U.S. 390 (1923)). When it was used to uphold individual rights, the Court did not usually refer to the specific rights protected in the first 8 amendments.
As the mid-20’s arrived, and substantial questions about the validity of the substantive due process interpretation were raised, the court began to rely more on individual rights previously referred to in the Bill of Rights. In 1925, for the first time, the USSC applied the protection for free speech found in the First Amendment to the states via the Due Process clause of the 14th Amendment. Eventually, the Court decided to reject the use of its “substantive due process” interpretation, and instead began to decide whether each specific right found in the Bill of Rights was “so rooted in the traditions and conscience of our people as to be as fundamental.” (Palko v. Connecticut, 302 U.S. 319, 325 (1937)). All of the provisions of the First Amendment have been “selectively incorporated” into the Due Process clause of the 14th Amendment.
One should note for completeness’ sake that the Court has continued to expand the meaning of “liberty” beyond the rights found in the first 8 amendments. When a right is deemed “fundamental” enough, it gets protection under the 14th amendment. This has been held to include the “freedom of association” (see the thread discussing the Boy Scouts), the right to vote and participate in the electoral process, interstate travel, and a “right to privacy” that includes freedom of choice in marital decisions, child bearing, and child rearing. It is the right to privacy that gave rise to Roe v. Wade.
Also, though I can’t get FindLaw to divulge its name today, there was a case not too long ago in which the USSC struck down a state law using the P & I clause, which has been a dead letter since the Slaughter-House Cases. It quite shocked everyone, and no one is certain if it will open a new avenue to restraining states from legislating in ways that interfere with personal rights.