Oliver W. Holmes Jr. held that what matters in legal theorizing is what judges do in fact, not what judges should do in theory. The public law litigation model offers an example of this realist approach to judicial activity by illustrating how much of an unclear judicial behavior is given by fact uncertainty. I first identify the changing features of public law litigation. If traditional conceptions of adjudication see litigation as a bipolar, retrospective, self-contained, and parties-controlled mechanism, today’s public law litigation is a multipolar, prospective, expansive, and judge-controlled type of judicial adjudication. In discussing how these changing features impact on our comprehension of fact uncertainty, I focus on the contrast between legislative and adjudicative facts. Finding and evaluating facts are directly related to the normative construction of State’s duties of care. This consequence can be exemplified by uncertainty about facts in environmental law cases.