Essay:Moral luck
A thought experiment:
On the same night, on the same road, but at different times, two drunk drivers pass out and swerve off the road. The first man kills a child, the second man only crashes his car.
Both drivers' choices to drink and drive were identical but one committed manslaughter. Their actions were the same, but their punishments are greatly unequal.
The first man had the bad luck of running down a child. The second man had the good luck of crashing harmlessly. The first man is going to jail. He might even go to hell. The second man is just going to the dealer to get a new car.
As far as their free will was concerned, each driver contributed exactly the same to their respective situations. The only difference was in the chance selection of a victim for the first man.
So it turns out moral responsibility is not solely defined by a man's decisions. Moral status can be partially beyond one's control. A lucky man can have greater morality than an unlucky man.