Safety problems can be costly and catastrophic. Engineers typically rely on assurance cases to ensure their systems are adequately safe. Building safe software systems requires engineers to iteratively design, analyze and refine assurance cases until sufficient safety evidence is identified. The assurance case development is typically manual, time-consuming, and far from being straightforward. This paper presents a manifesto for our forward-looking idea: using assurance cases as data. We argue that engineers produce a lot of data during the assurance case development process, and such data can be collected and used to effectively improve this process. Therefore, in this manifesto, we propose to monitor the assurance case development activities, treat assurance cases as data, and learn suggestions that help safety engineers in designing safer systems.