Is filing a lawsuit against a father who does not provide for his family, squanders his money on alcohol and women, and abuses his wife and children considered an act of disobedience to parents?

Maximum effort should be made to advise the son before taking his case to court. If that is not possible, then there is no harm in suing him. This is not an act of disobedience (ʿuqūq), but rather an act of righteousness (birr) and obedience (ṭāʿah), because it deters him from sins and alleviates his transgressions.