Among many problems with Trump's citizenship executive order (such as its obvious conflict with the constitution) is a practical one: birth certificates, which are currently the primary proof of citizenship for those born in the US, are issued by state and local authorities. These agencies do not (and aren't equipped to) determine or record the immigration status of the parents.

This means that citizenship would no longer be established with a US birth certificate or any other primary document.

In practice, birth certificates would likely be accepted MOST of the time as establishing citizenship, but those listing parents with "foreign sounding" names would be subject to open-ended scrutiny and investigation. And years later, people born here whose parents are dead or unavailable might have no way to definitively prove that they're citizens.

@mattblaze Yes. To inherit my late wife's postal savings account here in Japan, I had to trace her extended family history back to the birth of her father. The full record is a dozen pages long, spanning three major changes to the law and the form of records. Everything was delivered by her home town city hall in response to a single request.

US recording systems are ad hoc and messy by comparison, minimum-passing-effort rather than best-in-class.