So I just read Chief Justice Fuller's dissent, joined by Justice Harlan, in Wong Kim Ark, the 1898 case that established the 14th Amendment's birthright citizenship reading we adhere to today. And I learned something.
In 1873's Slaughterhouse Cases, a 5-4 Court rejected birthright citizenship and corporate personhood. I knew Justice Field, the lead dissenter, used his 9th Circuit duties to establish corporate personhood at the appeals level, thus seeding its SCOTUS recognition in the 1890s.
Turns out Field used his 9th Circuit duties to establish birthright citizenship in the same manner he had for corporate personhood, with his eventual victory over the Slaughterhouse majority coming three decades later. Per Fuller's Wong Kim Ark dissent: 
Field was one of the most odious men ever to sit on the court. That fact - and his circuit-riding subterfuge - is often used to discredit the origins of corporate personhood under the 14th Amendment. But does that same biography and dynamic also undermine birthright citizenship?
I'd argue no: Slaughterhouse was wrong for the sake of right, and on its surface-level substance, Field had the better argument. But Miller's majority gutted the 14A's privileges or immunities clause because he knew the better reading was a Trojan Horse for white supremacy.
John Campbell, a former SCOTUS justice who resigned to join the Confederacy, engineered a test case to kneecap Louisiana's Reconstruction government by using the 14A's most expansive clause against itself and attract the big business unionists among the justices. It was a trap.
Justice Miller's majority saw the trap, and saw the only way to avoid both constitutionalizing laissez faire in the 14A and kneecapping Reconstruction governments was to severely limit the one clause in that amendment meant to most robustly protect civil rights.
But that didn't mean Miller had to also deny birthright citizenship. In doing so, he handed a fig leaf of moral righteousness to Field's otherwise cynical use of civil rights to promote his own plutocratic agenda in partnership with lawyer Campbell's white supremacist aims.
In other words, just because Field was awful doesn't mean he was wrong on birthright citizenship, even if he backdoored its constitutionalization through circuit-level defiance of a (bad) SCOTUS precedent.
