On Sept. 8, 2015, plaintiff Steve Kim, 37, was driving on the westbound side of Olympic Boulevard, in Los Angeles. A trailing vehicle operated by Yeong Sim attempted to make a lane change to avoid traffic. Sim struck a vehicle operated by Brittney Ojeda. The impact caused Sim’s vehicle to move back into Kim’s lane, where it struck Kim’s vehicle. Kim claimed to his neck, back and a shoulder. Kim sued Yeong Sim; the owner of Sim’s vehicle, Sang Don Choi; Brittney Ojeda; and the co-owner of Ms. Ojeda’s vehicle, Juan Ojeda. Kim alleged that Sim and Ms. Ojeda were negligent in the operation of their respective vehicles. She also alleged that Choi was vicariously liable for Sim’s actions and that Mr. Ojeda was vicariously liable for Ms. Ojeda’s actions. Several of the defendants were dismissed from the case, and the matter ultimately continued against Sim only. Sim admitted liability for the accident., Kim claimed he suffered a rotator cuff tear of his dominant shoulder, and soft tissue to his neck and back. He presented to a chiropractor the day after the accident and then underwent a few months of chiropractic treatment for his neck and back. Kim also underwent a rotator cuff repair surgery to treat his shoulder. The plaintiff’s expert orthopedic surgeon opined that the subject accident caused Kim’s shoulder injury. The plaintiff’s expert biomechanical engineer opined that the force of the subject accident’s impact was sufficient to cause to Kim. Kim claimed he is now pain-free. Kim sought recovery of past medical costs and damages for his past pain and suffering. Defense counsel argued that there was no mechanism for a right shoulder injury as a result of the accident. Counsel argued that, instead, Kim’s shoulder injury was pre-existing and caused by his golfing, which Kim did weekly, and an injury to the same shoulder, for which Kim sought urgent care treatment approximately one year earlier. The defense’s expert orthopedic surgeon admitted that Kim could have suffered minor neck and back , but opined that Kim’s shoulder injury was not caused by the subject accident. The defense’s expert biomechanical engineer opined that the forces of the impact were less than those of walking into a wall.