Atticus is under intense pressure from many citizens in the town to not properly defend Tom Robinson at trial; however, he holds himself and his professionalism to high standards, and not not defend Tom would violate his ethical obligations (and his moral values).
Charlie has an IQ of 68, and has been selected for an experimental procedure to increase it. The doctors involved have taken an oath to do no harm, but they seem motivated more by fame than by the ethics outlined in their profession.
INHERIT THE WIND
Mr. Jaggers takes Abel Magwitch on as a client, even though he knows he is an exiled convict. When he finds out that Magwitch has returned, he has an ethical obligation to report him. Instead, he makes Pip have a very careful hypothetical conversation about Magwitch.
Despite the fact that it is illegal to teach evolution in school, Bert Cates disobeys the law and reads to his students from Darwin's "The Origin of Species."