Innocent until proven guilty?

So under our justice system it is claimed all are innocent until proven guilty! Yet recent reports by the CIA " a government agency" , that is suppose to abide by our laws .. Claims there are perhaps 100 detainees of Git mo , whom can not be released because "they are dangerous " , yet they can not be tried because of " lack of evidence"?? So "innocent until proven" only applies when a government "for the people by the people " , deems it necessary ? Does this also apply to the rest of us? Or only those chosen few of the world?