Over the years, the Second Amendment has been whittled down by myriad federal and state laws against possession of firearms by certain classes of people and against certain types of firearms.
Most offenses involving a firearm have nothing to do with whether or not you used or intended to use the weapon. The most common federal firearms offenses are triggered when someone is in possession, including constructive possession or joint possession, of a firearm after being convicted of a felony, misdemeanor crime of domestic violence, under a domestic violence protective order, or while being a drug addict or illegal alien. For those classes of persons, the mere possession will trigger serious federal charges. Federal law also makes it a crime to purchase a firearm for someone who is a felon. Under federal law, the ban on firearms also includes a ban on ammunition and possession of any ammunition will trigger the same penalties which include up to ten years in prison under normal circumstances, or life, under certain enhancement provisions.
Under state law, it is unlawful to possess a firearm in a number of places including schools and airports. We have successfully represented many businessmen in state court who are licensed to carry a concealed weapon, but completely forgot that their gun was in their travel bag when going through a restricted area. If you are at the airport and forget about your gun until it's too late, you will be arrested and charged with a felony. Because the offense was committed once you entered the airport with the weapon, the TSA have no discretion to let you run back to your car and put the gun away. Additionally, TSA will also seek a fine of several thousand dollars for the offense, in addition to the criminal penalties imposed by the State of Texas.
Under state law, it is well established that a person who is traveling has a right to possess a handgun for personal protection. However, Texas bans the carrying of concealed handguns without a license. Therefore, a legislative change made it lawful to for anyone in a private vehicle who was not engaged in criminal activity or otherwise barred from possessing a firearm was "presumed to be traveling," and thus exempt from restrictions on concealed handguns. Therefore, under state law, it is lawful to possess a handgun that is not in plain view in a motor vehicle as long as the person is not engaged in criminal activity, a member of a criminal street gang, or otherwise prohibited from possessing a firearm.
In terms of "rehabilitating" someone who was previously prohibited from possessing a firearm, while someone might be "rehabilitated" under state law, and thus, entitled under state law to possess a firearm after suffering a felony conviction, federal law trumps and will make the possession a federal crime nonetheless (except under very rare and limited circumstances).