In exploring sports ethics as a sociological phenomenon, I have tried to demonstrate how alterations in the nomos of the field of competitive practices (in the sense of Bourdieu), have unexpectedly unleashed a chain of events that have ultimately weakened the ethical principles of modern sport, imposing contradictions upon the way these are manifested in practice. Our theoretical approach to ethics was developed from the contribution of Durkheim, Weber and Elias.The universe of our study was the Portuguese reality during the Democratic state as a case study of the phenomenon. The information collected in our research has required different methods of analysis (qualitative and quantitative) and sources of data (official statistics, news from media, participate observation and interviews).Of the changes that took place in the last quarter of the 20th century in the Portuguese sports field, I have identified the inextricable interdependence of sporting, economic and symbolic dimensions as the main determining factor behind the victory-oriented approach to sporting action, which in turn has led to a radicalization of rival interests and an intensification of competition.As a result of this, there have been changes in the ethos of sporting interaction, weakening the principle of fair play and leading to an increase in practices that undermine it. This has meant that refereeing has become much more difficult, with increased distrust in the fairness of the competition, a situation which is aggravated by cases of corruption and doping. In this context, actors and organizations have become more involved in the ethical regulation of their sport in the Portuguese society. As a result, regulation has become more flexible and open to negotiation, both through institutional channels, and through strategies of pressure and persuasion in the (highly mediatized) public sphere. Thus, contingent solidarities have been strengthened to the detriment of organic solidarities.The growing distrust, together with the dynamics of surveillance and supervision launched in the 1990s, have also contributed to the activation of mechanical solidarities within groups with shared interests, in a context of opposition-confrontation or radicalization. This has been propitious to manifestations of collective violent revolt, and to the institution of forms of premeditated violence between some groups of ultra fans. Consequently, the undermining of ethical regularization has become even more visible, particularly in the field of top-level professional football.In response to the specific nature of the ethical conflicts in the sports figuration, states have intervened at national and European level by enshrining ethical principles in the form of legal provisions, defining systems of sanctions and penalties. This has resulted in a weakening of the autonomy enjoyed by sporting organizations, a principle that ultimately derived from the freedom of sporting associative movement in civil society.