Justice Clarence Thomas penned a lengthy dissent, which Justice Neil Gorsuch joined. He called the majoritys account not historically accurate and said that it adds to the sad history of the Fourteenth Amendment, which was designed and understood to secure equal rights for the freed blacks but has instead been repurposed for political projects that the Reconstruction Congress did not support.
Gorsuch also wrote a separate brief dissent, in which he appeared to suggest that Trumps executive order might violate the Constitution as it applies to the children of undocumented immigrants who intend to live in the United States permanently. If those parents are not domiciled here, Gorsuch queried, then where are they domiciled? And if the answer is nowhere, he continued, how can we reconcile that conclusion with this Courts longstanding recognition that every person is domiciled somewhere? Because the challengers in this case have argued that Trumps order is invalid in all circumstances, rather than just some, Gorsuch explained, these questions may not be properly before us. But their answers are undeniably important to a Nation committed to a view of citizenship open to all children born here to parents who can call this country their home.
Thomas is, in that bit, arguing for Congressional intent. Not much different from liberal dissent to a conservative-majority opinion a few days ago.
Gorsuch is digging into what 'domiciled' means. It means have a permanent place of residence, one that you are obviously committed to. Since people in the country illegally cannot be here legally and are subject to deportation, they cannot be legally domiciled.
The poster upthread that mentions 'allegiance' is also talking Congressional intent, but with reference to Wong Kim Ark where having no intent to return was taken to construe allegiance and was part of the opinion that is widely cited.
I'd add that the radio today blurted out--I don't know if it was a lawyer or Congressman (yes, apparently male)--that to rule otherwise would avoid the 'clear and plain meaning of the text.' I think that applies to a lot of the Constitution and numerous other laws, too, but 'holistic readings' and 'Congressional intent' where only a few out of scores of representatives are represented are often used to circumvent 'clear and plain' readings, so that strikes me a thin reed of support. The one caveat to 'clear and plain' readings are that sometimes syntax and more frequently lexemes change meaning and for that, fortunately, there is enough contextual and even explicit support for some meanings and readings to be well grounded in what the text 'plainly' or 'clearly' meant.