Facts
Neither parent is a paragon of virtue. Sally has a temper, and even bit her husband during a fight in front of the children. Ned tends to drink too much and then becomes an argumentative authority figure.
Action
A forensic mental health professional was hired to interview the family and others who know the family to write her observations in a report which the judge would use to determine the custody and visitation issues concerning the family.
Result
Sally was made the domicile parent because during his interview, Ned said that he was a better parent when he was sober. He then was given visitation privileges but with the caveat that he not drink while with the children.