Felons and Voting

There are 12 states that bar felons from voting.
Being a felon can definitley mess up the way that society views a person. They made a mistake... a BIG mistake and have been punished for it... jail, prison, parole, or probation... does that mean that felons should not be allowed to help in the decision of who our nation's leader is? I don't think so.
In my opinion, I believe that felons should be allowed to vote, but only on certain terms that prove them to be good decision makers.
For example: A person who commited a crime, was found guilty, served time in jail and also served time on probation. They have been punished and have kept their nose clean... Now, that person has done their time and paid their dues. They should be considered a normal, law-abiding citizen. Innocent until proven guilty, right?? Or will society continue to punish a person for the rest of their lives because of one mistake? One moment of bad judgement?
Consider a father and son relationship for a minute. The son decides to take dad's car out for a joy ride after curfew one night. Bad judgement? Let's keep going... The son comes home and dad is NOT happy because the car has a scratch. So, he grounds his son for 2 weeks and makes him work off the repairs to the vehicle, which he does and pays his father back in full. Sound's fair right? Okay, 4 months down the road the son asks his dad to borrow the car for a job interview. Should the dad ground him again for 2 weeks just for asking? I don't think so. Should the dad's reaction be to tell him no? maybe. But it's important... it's important for both of them because the son is trying to be responsible and get a job and for the dad, it's also important because if his son wasn't trying to get a job, he'd end up supporting him his whole life.
I understand that felons should be punished for their wrong-doings, but if they've done their time and care enough to vote for who their leaders will be, then I think they've shown enough responsibility to have earned that right.