Member States shall put in place national rules for the award of contracts subject to this Chapter in order to ensure contracting authorities comply with the principles of transparency and equal treatment of economic operators. Member States are free to determine the procedural rules applicable as long as such rules allow contracting authorities to take into account the specificities of the services in question. Member States shall ensure that contracting authorities may take into account the need to ensure quality, continuity, accessibility, affordability, availability and comprehensiveness of the services ; the specific needs of different categories of users, including disadvantaged and vulnerable groups ; the involvement and empowerment of users ; and innovation.