Many countries employ "alternative access schemes" (e.g. compassionate use, early access programs, off-label use) that seek to provide patients with access to drugs not included on a positive drug list. These schemes offer flexibility to policy-makers but often lack transparency and clear rules. This ambiguity allows for dynamic responses to weaknesses in the main drug approval and reimbursement systems, but also opportunistic use by the health professionals, industry or patients. Yet, most descriptions of these schemes focus on the de jure rather than the de facto situation, presenting a potentially misleading picture. We describe one such scheme in practice: the Slovak "extraordinary reimbursement regime" (ERR), using semi-structured interviews with 18 experts and a new dataset of ERR drugs. The ERR expanded rapidly, doubling between 2012 and 2016. It combined features of four reimbursement schemes: (1) a backdoor market access for expensive drugs; (2) a compassionate use scheme for investigational drugs combined with a "legacy drugs" scheme for older unlicensed drugs; (3) a disease-specific scheme for cancer and orphan drugs; and (4) a scheme for off-label and "off-indication" drugs. These four features reflect broader challenges facing the Slovak reimbursement system. We conclude that detailed study of the type, size and evolution over time of alternative access schemes can serve as indicators of health policy objectives neglected by standard reimbursement systems.