Operating after Suspension is exactly as it sounds. For one reason or the other, the State of Maine has suspended your license to drive, and you get caught driving. A basic first offense bears a mandatory minimum $250.00 fine with every conviction thereafter bearing a $500.00 fine.
Though the explanation of an OAS is rather simple, there are several things that the State must prove in order to convict a person of OAS that are not necessarily always so straight forward.
First and foremost, this may seem obvious but the State must prove that the Defendant was actually driving. Again, this may seem rather simple. Not every instance is the same however. Sometimes a police officer will see somebody driving or see a license plate that he recognizes, say to himself "oh, I know that guy, he's suspended!" then track the person down later and serve him with a summons for OAS. The problem for the State in such a scenario is that you are either dealing with the eye-witness identification of a moving target (not always reliable) or the officer is simply assuming that the suspended person drove the car.
Even if the officer runs a plate, pulls the car over, and boom the suspended person is sitting there in the driver's seat with his hands on the wheel and he is alone in the car, then sometimes there are issues revolving around the legality of the stop which can be raised in the driver's defense. If their is a legal problem with the officer's stop of the vehicle, a criminal defense attorney can identify those issues and potentially suppress any evidence gathered as a result.
The State must also be able to prove that proper notice was provided to the person that his license was set to be suspended. Now, this does not necessarily mean that the person has actual knowledge that they are suspended (though if the State can prove that, it is sufficient) rather, the bare minimum standard the State must meet is a showing that effective notice of suspension was sent to the last known address recorded with the Bureau of Motor Vehicles.
This means that if you have moved, but never updated your driver's license, and the State sends the notice to the address listed on your license (because that is what is recorded at BMV) then that is considered sufficient notice.
But despite this shamefully low standard that the State has to meet (it is literally the bare minimum) the State still fails on a semi-regular basis to provide sufficient notice. An attorney familiar with parsing out you BMV motor vehicle history records and court records will be able to identify this issue if it is present in your case.
OAS and OUI
At this point I want to point out a rather serious elevated risk involved with license suspensions resulting from an OUI (drunk driving) arrest.
If you are arrested for an OUI, the Secretary of State will at some point levy an administrative suspension against your driver's license (more on that here). That suspension lasts for a minimum of 150 days, and if you are caught driving during that "initial" period of the suspension (150 days) then the penalty for violating the suspension will not be the standard $250 or $500 fine as referenced above. Instead, the mandatory minimum sentence imposed by the court is two weeks in jail. Two weeks. You could be doing something as innocent as driving to the store so you can feed your kids or driving to work, and you (if convicted) will be sentenced to spend two whole weeks in a county jail. It does not matter if you only drove 200 feet down the road or if you never had a criminal record before the OUI arrest. The consequences are serious, and they are mandatory.