The enumeration in the Constitution, of certain rights, shall not be construed to deny or disparage others retained by the people.When they declared indepence, they didn't do so for ALL of the people governed by England, just those over here. Not very different from just a state seceding.
I could easily see California deciding to do so if things like [link|http://www.chron.com/cs/CDA/ssistory.mpl/nation/1765007|this] keep happening. The feds obviously don't have the consent of the governed in this situation.