More precisely that it is still being laid down whenever a higher court creates precedents indicating which legal theories are and are not to be interpreted as having force.
Granted most of the significant features were accreted by the late 1700's, and for the interpretation of the Constitution that part of it has partciular relevance since it frames the context in which the Constitution was written.
I will have to track down a lawyer to discuss this with. Possibly at Thanksgiving because then I can get 2 of them to argue with each other... :-)
Cheers,
Ben