Legal Question in Personal Injury in Maryland

If you son was maintaining a safe distance he should have been able to avoid colliding with the motorist, even if they stopped unexpectedly. The other driver shouldn't have left the scene if she did so before identifying herself and her insurance company, although from your question it sounds like she did so, unless all he did was take down her tag #. In either event, her insurance company isn't going to take responsibility. If she doesn't make a claim against your son, he'll be lucky. He should get insurance and a license if he plans to use the public roadways.