The Declaration is -The Plan. That Plan was to have a very strictly limited government — but powerful enough to do its job.
The Constitution has become, in the minds of the people, The Perception as to what is happening. The Perception, by many people, is that the government is only doing what is necessary to maintain a peaceable society.
The Practice is what the government does. That Practice, when compared to The Design, has returned us to the 1776 style of Tyranny and Despotism — on steroids. It no longer reflects the limitations against government powers detailed in The Constitution.