Natural Law ethics sees right and wrong as fixed concepts that can be deduced through reason. He argued individuals' reason could be used to reveal certain primary precepts that are good, for instance, protecting life and ensuring reproduction. Catholic thought, heavily influenced by Natural Law, would put forward the argument that sex is something that should be subject to social norms and legislation, as sex is linked to new life, to stability, community and commitment. The argument can be made that homosexual sex, pre-marital sex and extramarital sex should be restricted by social norms or legislation in extreme cases. It may be the most ethical course of action to prohibit sexual behaviour that is not beneficial for sustaining human society but in fact hurting society. Homosexual sex cannot bring forth new life and bringing new life outside of marriage does not ensure that a child is nurtured in a stable way. This would support the view that sexual behaviour should be subject to social norms.
On the other hand, it could be argued that traditional ethical rules surrounding sex are too restrictive on individuals. Social norms which perceive married heterosexual couples as the only legitimate relationship in which sex can take place, ultimately leads to the oppression of minority groups and repression of individuals sexual desires. The case can be made that this restriction of the individual is an unethical approach to sexual behaviour in our society.
Situation Ethics permits the setting aside of social rules, if that is the most loving thing to do, Fletcher argued that this could be applied to sexual ethics. For example, a married woman whose husband is suffering from Alzheimer's may seek an extra-marital relationship which offers her the support and care that she needs while caring for her husband. If extra-marital sex was prohibited by legislation, for instance, this woman would suffer from the absence of emotional support she would receive from a loving relationship as she cannot divorce her ill husband and there are laws restricting her from seeking that love somewhere else. This example highlights how sex being regulated by legislation may lead to negative consequences for society, causing more pain than pleasure. In these situations, it may be more ethical to abandon sexual ethical rules that prohibit extra-marital affairs.