Thanks to Cole Simmons for mentioning this. The problem: the Declaration of Independence does not have legal standing. One could say it’s like acid on nearly any set of laws. An appeal to “nature’s God” could yield anything.
The problem was very acute when slavery was legal. “All men are created equal” did not ennoble all Americans. “Liberty for all,” then, needed to be seen as setting us in motion. Lincoln is emphatic it comes from the Declaration. He describes the revolutionaries as “oppressed:”
No oppressed, [sic] people will fight, and endure, as our fathers did, without the promise of something better, than a mere change of masters.
The pursuit of liberty involves understanding all as equal in some way. At the least, we fight oppressors together. A parallel exists between the spirit of the laws and the laws themselves:
[The assertion "Liberty for all" was] the word, “fitly spoken” which has proved an “apple of gold” to us. The Union, and the Constitution, are the picture of silver, subsequently framed around it.
The laws should aid equality in order to bring us to liberty. This does not mean communism, but working with a near perpetual tension between opportunity and dignity. Slavery removes dignity from the picture. The “fighting” – the base, essential assertion of right – is inherent in the law truly conceived.