Star Trek: Voyager - 10 Greatest Doctor Episodes
3. Critical Care
Providing medical care to anyone who needs it regardless of who they are is what the Doctor is programmed to do. But when he is forced to leave seriously ill people to suffer and die, he cannot stand by and let it happen. He takes matters into his own hands and finds he is capable of doing things he never imagined.
After being stolen from Voyager and sold to a society who provide medical care based on a predetermined value to society, he finds himself in a difficult situation. He is forced to provide preventative care for patients who aren't sick while people gravely ill are left with limited medication.
When the Doctor forms an attachment to a patient who is later killed, he resorts to behaviour he later questions.
He deliberately infects the supervisor responsible for the patients with a deadly disease and withholds treatment until he agrees to change the system. When he returns to Voyager, the Doctor has his program checked to ensure his ethics routines are functioning properly, and they are.
He then realises that his actions were a conscious decision that he made based on his emotions. This is a massive moment of self-growth for him, as it is clear he is now becoming more human than technology.
It's an excellent storyline for the Doctor which also provides commentary on medical care in society today.