And that's the important context I keep referring to, that DL omitted. When we separated from England, we didn't end up with no law (the "state of nature" Madison refers to), or only state laws. But the new federal government didn't sit down and write all new laws to cover everything, either. So then what was the law? What would be the basis for figuring it out? Clearly, Madison thought the "civil rights and obligations"--i.e., applicable parts of the common law--continued after independence.
Good point.