Khalif Jones (plaintiff) filed suit in state court against L.A. Fitness International, LLC (LA Fitness) (defendant) after he was injured while playing basketball on an indoor court at one of LA Fitness’s health clubs. Jones had struck the back wall, dislocating his elbow. Jones’s complaint alleged that LA Fitness was negligent for failing to make the basketball court safe and for failing to warn persons of the dangerous condition of insufficient padding on the back wall. LA Fitness timely removed the action to federal district court on the basis of diversity jurisdiction. LA Fitness filed a motion for summary judgment and to preclude the testimony of Jones’s expert witness, Steve Bernheim, as inadmissible under Federal Rule of Evidence (FRE) 702. Bernheim, a sports and recreation consultant, concluded that the basketball court failed to comport to national standards, including insufficient clearance between the baselines and the back wall and insufficient padding along the back wall. LA Fitness argued that Bernheim was not qualified to offer a medical or biomechanical opinion. The district court reviewed LA Fitness’s motions.