That’s exactly what that case was. It grated Equal Protection Rights to corporations as well as Natural Persons. That’s then what is referred back to as the case law when “Is a corporation a person?” comes up.
A headnote issued by the court reporter in the 1886 Supreme Court case Santa Clara County v. Southern Pacific Railroad Co. claimed to state the sense of the Court regarding the equal protection clause of the Fourteenth Amendment as it applies to corporations, without the Court having actually made a decision or issued a written opinion on that point
… It’s then referenced as if it was part of the verdict in Singer Manufacturing Company v. Wright the next session where Justice Newman’s opinion confirmed it explicitly.
“[…] it is now considered settled, I presume, by the language used by Chief Justice Waite, speaking for the supreme court, in the case of Santa Clara Co. v. Railroad, 118 U.S. 396, 6 Sup.Ct.Rep. 1132, that corporations are so included and entitled, as fully as natural persons, to its protection”.
Yea, I get that it likely wasn’t what was decided in the original case, but to claim that case isn’t what the justices use to define corporate personhood is ignorant.
The much more egregious error that is referred to is Qualified Immunity, which seems to have been invented whole cloth by a scribe during the first time US laws were collated when he incorrectly wrote down a law.