[P-Marlowe]

Under “Natural Law” were slaves and the children of slaves born in the land considered Natural Born Citizens?

Or was Natural Born Citizenship conferred on the basis of existing statutes?

[Cboldt]

-- Under "Natural Law" were slaves and the children of slaves born in the land considered Natural Born Citizens? --

That's a really good question.

-- Or was Natural Born Citizenship conferred on the basis of existing statutes? --

No, US citizenship was and is conferred by operation of the US constitution.

Article IV, section 2. The Citizens of each State shall be entitled to all Privileges and Immunities of Citizens in the several States.

Affected by the 14th amendment. 1. All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside.

Congress has plenary power to define naturalized.