Opponents of a freestanding cultural defense also argue by the principles of fairness and justice. A legal system should have only one standard, and immigrants and other minority groups must learn its rules and values. Otherwise, those who know the rules, regardless of their race or national origin, would be treated more harshly and thus unfairly compared to recent immigrants committing the same criminal acts. Furthermore, victims of those who do not know the rules will be offered less protection.

Women's advocates are also concerned that a formal cultural defense is unfair, especially to immigrant women, because it eliminates the limited progress achieved in areas such as domestic violence and marital rape. Because violence against women is still so widely accepted and approved in cultures across the world, cultural background can easily be used to justify or excuse the perpetrator's actions. Members of immigrant communities who should otherwise be protected by the law are at risk of further violence. Victims of immigrants, particularly their partners and children, would receive unequal and less protection than the non-immigrant population.

Furthermore, immigrant communities already often express their concern that crimes with immigrant victims are punished less severely than cases in which the victim is white. For example, a Hmong man received probation after sexually assaulting his two stepdaughters because his attorney argued that, "'he is from Vietnam. . . Part of what happens in an agrarian culture, sometimes young girls are married and that may have been a carry-over in their culture. . . . This behavior may have seemed to be OK or not as bad as we view it.'" A spokesman for the victims' family countered, ‘There are no cultural differences to allow a man to molest children that age. . . . The family of the victims were shocked.'"(Molester's Probation Shocks Kin, Capital Times, August 29, 1996, at 3A). They compared this sentence of probation to an earlier case involving a young white girl. The girl's stepfather was sentenced to 10 years in prison for sexually assaulting her. (Meg Jones, Sex Assault Sentence Draws Charges of Bias, Milwaukee J. Sentinel, Aug. 29, 1996, at 1).