In February 2023 the ‘Trans Law’ was passed in Spain. This law generated considerable controversy. It was opposed not only by the radical right and the centre-right, but also by some socialdemocratic sectors linked to traditional feminism, who accused it of allowing the ‘erasure of women’. The feminist movement was divided and the positioning on this issue did not seem to reproduce a purely left/right logic. This cultural war seemed to be yet another example of the polarisation in this country, albeit along different group lines. We used original data from the III and IV National Polarization Survey to demonstrate which variables explain support for this law. Specifically, we seek to corroborate whether ideology was not a key explanatory factor (given that certain left-wing sectors opposed it) and whether women showed a more sceptical attitude towards this issue, breaking their greater tendency to show support for progressive policy proposals. Finally, we analyse to what extent partisan biases were reproduced in this case and how other socio-demographic variables played a role. The results show that support for the Trans Law clearly reproduced the left/right divide, that women supported this law more than men (there is no majority cultural backlash against it on their part) and that, although it was the alternative left that was most enthusiastic about trans rights, social democratic voters were also supportive. In short, trans rights reproduce divisions already present on other issues and have not generated new lines of rupture in Spain.