The study aims to define «political turncoatism», an ambiguous concept that includes very different circumstances. This article proposes a strict definition, which only applies to those who switch to an opposing party for spurious reasons. Then, «turncoatism» becomes pathological for democracy. The study analyzes the minutes of the supervision commission, that was created by the anti-turncoatism Agreements of 1998, with the intention to show the real dimension of the problem. Despite the impact of turncoat cases in the media, the number of desertions is very low. The article addresses the models of political representation as a previous question. The rule of free mandate �the members of the Parliament are not bound by an imperative mandate� has full sense as a limit to partyarchy and as an instrument of division of power. Finally, the study reviews different measures to deter representatives from deserting. Alternatives to the revocation of the representative by the intention of the political party �that is not allowed in democratic Constitutions� must be considered.