Under the U.S. Supreme Court's legal standard for determining civil liability in Fourth Amendment excessive force cases, jurors must judge the reasonableness of an officer's use of force from the perspective of a "reasonable" officer on the scene by considering factors like a suspect's threat and resistance levels. However, despite a growing body of empirical work on judgments of police use of force more generally, research has yet to examine whether jurors adhere to the reasonable officer standard. To help fill this gap, the current research reports on two online experiments that manipulated suspect threat and resistance levels, along with suspect race and perspective-taking in the form of expert and social fact testimony suggesting what a reasonable officer would do in similar circumstances. The results showed that suspect threat level and perspective-taking information indirectly affected officer liability decisions through officer reasonableness judgments, but that suspect resistance level did not. The results also revealed the influence of various extralegal factors outside the legal standard on reasonableness judgments and liability decisions, including attitudes toward police legitimacy and feelings toward the Black Lives Matter movement. Thus, the findings across both experiments showed that mock jurors adhered to some aspects of the reasonable officer standard but that their own sentiments still influenced their legal determinations. Finally, expert, and social fact testimony related to use of force assisted mock jurors in making officer reasonableness judgments and liability decisions when applying the reasonable officer standard. Implications of this research for psychology, law, and policy are discussed.