In 2012 the Swedish government introduced national legislation stating that all elderly patients using multiple medicines should receive medication reconciliation and, if necessary, a comprehensive medication review. This case study investigates how and why this legislation was developed and implemented on a national, regional and local level, with Uppsala County as the main example. To answer these questions, factors for change were identified from a desk review and key informant interviews using the domains within the Kotter’s Change Model and the Normalization Process Theory. Within all these domains both presence and absence of factors for change have been identified throughout this case study. Main facilitators were the presence of national health quality indicators and research studies showing the polypharmacy problem which led to political and public awareness, the engagement of key individuals and a broad collaboration at regional level, and investment in education and multi-disciplinary healthcare teams. Main barriers have been the lack of a common belief that medication review is an essential and effective intervention, the lack of a broadly shared view on how and by whom exactly these reviews should be performed, and the absence of a national strategy to fully implement and evaluate medication review legislation and policies. New initiatives for further implementation should make use of change management strategies, taking into account all necessary steps for change. The identified existing barriers can act as a starting point for following measures in which the performance of medication reviews should be seen as an essential but not exclusive activity to improve the care for elderly with multi-morbidity.