Could we do as we please without fear of criminal record (See details)?

There are some things you can do which can have long-term consequences, even if you have your juvenile record expunged. Some felonies will be treated as adult offenses. Some offenses will have penalties which can continue beyond your 18th birthday. Somethings you do could have long-term consequences on your conscience or your relationships with other people. Even if there are no legal consequences to what you do, there will still be lingering social consequences. You don't want to be that forty-year-old guy everyone points a finger at and whispers, "that's the guy who did that stupid thing over 20 years ago."