This article analyses the new ruling of the European Court of Human Rights (ECHR) ‘López Ribalda II’ and the possibility for employers to use hidden video surveillance cameras in order to monitor employees in the workplace. The criteria of the Spanish Constitutional Court and the first judgement of the ECHR in the ‘López Ribalda’ case are also studied in order to understand the evolving criteria and the importance of the new ECHR decision for the future of labour relationships. In short, the new ruling of the ECHR ‘López Ribalda II’ justifies the installation of hidden cameras due to the existence of reasonable suspicions of employee’s irregularities when this is a proportional decision and there are no less intrusive measures.