It DOES NOT MATTER what the circumstances of the accident were. Even if the guy was riding a black bike with black rims wearing black clothing and blacked out his face, the fact is that the car driver HIT him, KNEW he hit him, KNEW that he injured the guy seriously, then drove away.
Had he stopped to render assistance, depending on the circumstances he should probably have gotten anything between nothing (if proven that the guy was essentially invisible and completely in the wrong) to a reckless endangerment sentence (probably suspended or light time seeing that the guy didn't die) and I'd have very little problem with that.
Once he decided to drive away, it's felony hit-and-run and I hope he gets sent up for a couple of years. The fact that he took the time to go back and yell at a guy he just hit makes me hope for something unfortunate to happen to him while he's in jail.
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Work: the 8 hours that separates bike rides.