The issue of an armed citizenry is addressed most specifically in "The Federalist Papers" "Federalist No. 28", written by Alexander Hamilton.  It discusses the need for the public to retain its "original right of self-defense [,] which is paramount to all positive forms of government."  Hamilton goes on to state that this right, above all, is to protect the citizens against their governments, both state and federal.  This leads me to believe that it is the individual citizen who has the right to arm him/herself, because the government would never use the organized militia/military against itself as a tyrannical power.