The government is only legitimate so long as it follows the Constitution.
Nope. Being elected by the people gives the legitimacy to the government -- and that legitimacy includes the right to change laws and Constitution.
"The brief writerÂ’s version
seems instead to be based upon the proposition that federal
judges, perhaps judges as a whole, have a role of their own,
quite independent of popular will, to play in solving societyÂ’s
problems.
Once we have abandoned the idea that the authority
of the courts to declare laws unconstitutional is somehow tied
to the language of the Constitution that the people adopted, a
judiciary exercising the power of judicial review appears in a
quite different light.
a. Judges then are no longer the keepers of
the covenant; instead they are a small group of fortunately
situated people with a roving commission to second-guess
Congress, state legislatures, and state and federal administrative
officers concerning what is best for the country."
Chief Justice WILLIAM H. REHNQUIST
http://www.law.harvard.edu/students/orgs/jlpp/Vol29_No2_Rehnquist.pdf