This as has been rightly pointed out is a matter of STATE law and if the citizens of that State want convicted felons that are in prison to have the right to vote in that state then they can. On a personal level, it's my opinion that a person in prison should have no rights to vote as they are paying a debt to society and as such they are there because they showed contempt for the laws of society , so why then should society impart on them the privledge to vote under those laws. Once that debt has been repaid however, what I do believe is that these men and women should be accorded all the privledges of citizenship including the right to vote and to keep it from them is retro-active punishment for a debt in which they already paid. Sometimes when these rights are taken away forever, what they eventually do is lead to a sense of hopelessness on the part of people who have paid that debt and they end up commiting more crimes because they have little choice. So the laws after the fact tend to be self defeating. When I was in the Navy, back when the flintsones car was a new model the courts often used to sentence young people to serve in the Military and many of them went on to careers in the Military and served honorably.