Here's another take on the Texas v. White ruling in 1868.
In "the Politically Incorrect Guide to the Constitution" (2007) author Kevin Gutzman, J.D., Ph.D. wrote:
"In Texas v. White the Supreme Court declared that the Constitution "looks to an indestructible Union, composed of indestructible states," and ruled that in fact Texas had never seceded, and that Texans had been wrong to think otherwise. The ruling was five to three, with the majority decision issued by Chief Justice Salmon P Chase, a former Lincoln cabinet member (who arguably should have recused himself) whose logic was less than convincing. Its constitutional basis was in Article IV's statement that "the United States shall guarantee to every State in this Union a Republican Form of Government." Allegedly this proved that the Constitution supposed "an indestructible Union." The Latin phrase for such decisions is ipse dixit: asserted but not proved."
Texas v. White was not a 5-3 decision. It was a 7-1 decision. Five justices joined Chase in his opinion, while two others issued a separate, but concurring decision. Only Justice Grier dissented.
It was apparently convincing enough to get 4 other justices to agree with him.