The thread that connects the jurisdictions analyzed, despite the different theoretical backgrounds, is that courts divide the assessment of causation in a multi-stage process whereby the verification of the causal link has a strong empirical base. However, at any stage, causal uncertainty may render the assessment of causation extremely difficult if not impossible to perform. While the previous chapters have mainly dealt with the definition of the different concepts of causation from a comparative perspective, this chapter presents the main situations and elements of causal uncertainty, thus also introducing issues related to the proof of causation.