The primary purpose of Brian's character is to act as a foil to his wife Sara. A foil is a character who is set up as an opposite or contrast to another more primary character. The purpose is to highlight certain traits of the more primary character by drawing a direct comparison. In this case, I would not consider Sara to be unethical by nature, however, Brian's inherent goodness and integrity tend to paint Sara in an even more negative light. The main difference between these two characters is the different relationships they have with their children (as a result of different parental and gender roles) as well as the different ways they cope with stress. Because Brian is such a decent man, the audience more naturally sides with him over his wife.
As far as Brian's ethics are concerned, he is a devoted father, husband and firefighter. He puts in to all three jobs equal attention and positivity. He is not rich, but (main story line aside) seems happy. He is probably hardest on his son, as all fathers tend to be, but he admittedly loves his children equally and shows that he has a unique relationship with each one. He also admits that he isn't perfect, but tries to do the best with what he has. It is clear that he is well liked at the fire station, and respected by his daughters. Even his son, who is on the verge of dilinquency, eventually comes around, showing that his father, as a role model, has done an adequate job. Brian wants what is best for his entire family, and shows this by pushing Sara to allow the girls to decide for themselves what they want to do. Because of his more paternal sense of patience (mothers tend to worry more and show more emotion) the comparison between Brian and his wife paints Sara as the "bad guy" in the family. Brian's sense of right and wrong is very black and white, which is likely why it seems easier for him to come to conclusions on major decisions and seem less emotionally driven.
In the end, however, it is clear that Brian loves his wife and his children. It is also clear that he is equally (if not more) stressed about the medical/legal situation created by his daughter(s). Despite this, he makes an effort to keep things as normal and routine as possible.