The ruling should have been limited to the children of permanent resident aliens, as that was the case that was brought before the court. Somehow, the ruling expanded the universe to be all children born in the United States, not just the children of permanent resident aliens.
I'd like to know why?
-PJ
At the time, appeals were made to newly independent states to resist Communist expansion. One aspect was to liberalize enforcement of existing immigration rules and national origin quotas (deriving from restrictions of the 1924 and 1952 Immigration Acts).
The earliest official "birthright citizenship" consideration may be found in the "Petition to Classify Status of Alien Relative (I-130)" form of November 1964.
It states: "(5) If you are a citizen of the United States, give the following: Was your citizenship acquired through birth in the United States...?" (without a follow-up question or reference to parental status, thereby enabling an "anchor baby" status like that of Kamala Harris), but there may be others.