As one of the drafters of the Croatian Anti-Discrimination Act, Tena began working in the Office of the Ombudsman in 2008 to set up its equality body mandate. She was elected by the Croatian Parliament as Deputy Ombudswoman in 2013 and has overseen the institution’s non-discrimination and equality work ever since. As an independent expert, she is also a member of the Council of Europe's European Commission against Racism and Intolerance (ECRI), a member of ECRI Bureau and co-representative of ECRI to Council of Europe's Ad hoc Committee on Artificial Intelligence (CAHAI). She also delivers lectures and trainings and publishes on human rights, the rights of national minorities and particularly non-discrimination and equality law.