Why did the Plessy v. Ferguson majority consider the Separate Car Act a reasonable use of state police power?

In the majority opinion for Plessy v. Ferguson (1896), the U.S. Supreme Court held that the Separate Car Act was a reasonable exercise of state police power because it was intended to preserve "public peace and good order."1

Justice Henry Billings Brown argued that the law did not violate the Fourteenth Amendment because the amendment was intended to secure only legal equality, not social equality. The Court maintained that as long as the facilities provided for each race were equal, the law satisfied the requirement of equal protection. Furthermore, the majority asserted that legislation could not abolish social distinctions based on physical differences or "racial instincts," and that attempting to do so would only exacerbate social tensions. By framing the segregation of passengers as a matter of maintaining public order, the Court justified the state's authority to enforce separation, a doctrine that would later be overturned in Brown v. Board of Education of Topeka.21