The best way that I’ve found to think about it is that the Declaration is a legal brief, not a law. In other words, it’s an argument (to Parliament and the world at large) about what the law should be, not a statement of what the law is.
It’s our vision statement.
You can have my rocket’s red glare when you pry it from my cold, dead hands!
“Your honor, universal optical care is clearly a guaranteed right under the National Anthem, as otherwise my client might be unable to see for himself if our banner is gallantly streaming.”
Think of it as a speech in wrtitten form.