Legal practice is up to its neck in epistemology. Legal practice involves proof, evidence, doubt, testimony, arguments, witnesses, experts, and so on. The epistemology of legal practice, often referred to as legal epistemology, examines epistemological questions raised by legal practice. It can also apply legal insights to illuminating perennial epistemological problems. Legal epistemology investigates whether standards of proof, such as “beyond reasonable doubt” or “preponderance of evidence,” are best understood as credences, statistical likelihoods, or as qualitative standards. It asks what, if anything, legitimates these standards and in what ways legal standards of proof should be sensitive to practical factors. Legal epistemology examines when and why evidence has a probative value; that is, it investigates how evidence makes a litigated claim more likely. It illuminates what reasons—moral, political, economic, practical, epistemic—justify excluding probative evidence. It questions whether particular kinds of evidence are apt to mislead factfinders. Perhaps some kinds of character evidence, for example, are prejudicial. Legal epistemology asks whether particular aspects of evidence law contribute to epistemic injustice, including hermeneutical injustice, and illuminates sources of legal injustice. It investigates the normativity of profiling. Legal epistemology questions the epistemic and legal values of epistemic properties such as safety, sensitivity, reliability, coherence, intelligibility, knowledge, justification, explanation, narrative structure, epistemic virtue, and truth. Legal epistemology asks whether and how juries and judges can form collective beliefs; it examines features of effective deliberation and judgment aggregation, and studies the effect of disagreement and dissent on legal judgments. Legal phenomena such as expert testimony raise distinctive epistemological questions, such as how to adjudicate and manage expertise in the courtroom. Legal epistemology studies the legal posit of reasonableness, which arises in the reasonable person standard, reasonable doubt standard, and various other areas of legal practice. Legal epistemology can also illuminate the role of knowledge and ignorance in culpability: How should we understand the epistemic criteria for recklessness and negligence, for example, and what precisely is mens rea? Law varies by jurisdiction; different legal systems create and resolve epistemological challenges in different ways. This is evident in topics such as the admissibility of character evidence or hearsay evidence, the permissibility of inferences from silence, or the exclusion of improperly obtained evidence. Legal epistemology is deeply interdisciplinary. In addition to law and philosophy, it involves research in psychology, forensic science, sociology, anthropology, criminology, history, theology, politics, economics (particularly behavioral economics), artificial intelligence, computing, and statistics.