I know I just dealt with this subject at some length in reference to a couple of other films, but it wouldn’t be right to leave the topic without also referencing what may be the definitive film dealing with the issue: 1939’s Mr. Smith Goes to Washington.
While of course it is dated and features one of those shallow happy endings, the film’s portrayal of a cynical and corrupt Washington culture was very controversial – even scandalous – at the time. In that sense it was way ahead of its time; or to put it another way, timeless.
In the first few minutes of this clip the elder “compromised” Senator, played by the immortal Claude Raines, lays it all out for the puppy-eyed boy-Senator played by a young Jimmy Stewart, regarding the necessity of servitude to a corrupt political master named Taylor. I’d recommend the entire film to anyone who is interested in the questions raised by moral compromise. They have never been posed more poignantly than in this film, as summarized here: