Abstract: This article considers the type of evidence that an overseer (e.g., a court) should require before allowing a government agent to take some proposed action. The court can increase agency research incentives by prohibiting actions unless the agent produces supporting evidence, and/or by permitting action even when the agent uncovers adverse evidence. The court thus faces a trade-off between an evidentiary standard's ex post effects on the agent's policy decision and its ex ante effects on the agent's incentive to do research. An extension allows the court to make research effort a precondition for action, regardless of the evidence produced.