I'm Lucy, and I'd be happy to answer your questions today. I'm sorry to hear that this happened.
If there was an emergency situation such that your son was required to move the car despite not having a license, he can plead not guilty and request a trial. He has a right to have an attorney appointed for him, and he could defense on that basis. An emergency would be something like, someone needed to go to the hospital and couldn't unless that car was moved. Moving a car because the other driver was drunk likely isn't an emergency unless there was a reason that the car HAD to be moved to prevent an injury to someone else's health and safety and there was no one else sober to do it. A lawyer might also be able to dispute whatever sequence of events lead to the police asking to see your son's license.
The other option is to go in and try to make a deal with the district attorney. It's possible they'll be willing to lower the fine if you explain what happened. The minimum fine is $75. However, they'll probably suspend your son's ability to get his license.
Your son has a right to have a lawyer represent him, so he can also go to court, plead not guilty, request a lawyer, and let the lawyer try to negotiate the best possible outcome for him after reviewing all the evidence.
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