On July 22, 2011, at approximately 11:45 p.m., plaintiff Natalia Martin, 64, a registered nurse, was driving south on Park Presidio Boulevard in San Francisco when she entered the intersection with Lake Street and collided head-on with a vehicle operated by Arthur Lawrence, III, who was traveling north on Park Presidio Boulevard. Martin suffered fractures to her left shoulder, ribs, chest, and right ankle. Martin sued Lawrence, alleging the defendant was negligent in the operation of his vehicle. Martin claimed that Lawrence crossed over the centerline as he entered the subject intersection, causing the head-on collision. The plaintiff’s accident reconstruction expert testified that the angle of the impact on the damaged vehicles supported a conclusion that Lawrence’s vehicle had moved across the centerline. The expert further testified that, based upon the principles of physics, the undisputed points of rest of the two involved vehicles supported Martin’s version of the accident. Lawrence claimed that he remained in his lane of travel and that it was Martin who crossed over the centerline and caused the head-on collision. Defense counsel presented an eyewitness who was traveling behind Martin at the subject intersection. The witness testified that he was approximately 50 to 200 feet behind Martin when he clearly observed Martin’s vehicle suddenly speed up and move left across the centerline, resulting in the collision. However, the plaintiff’s accident reconstruction expert opined that the witness’ vehicle was more likely 180 to 238 feet behind Martin’s vehicle. Defense counsel attempted to present the investigating police officer’s traffic collision report, which found the area of the impact to be entirely within Lawrence’s northbound lane of travel and, accordingly, found Martin to be the sole cause of the accident. Counsel also attempted to call the investigating police officer to testify as a non-retained expert witness. However, following a Voir dire of the officer outside the presence of the jury, Judge Marla Miller ruled that the officer could not testify regarding his opinions as to the area of impact or as to fault. She reasoned that the officer did not have sufficient facts from which to reasonably rely upon to support his opinions., Martin sustained fractures of her left clavicle, two ribs on her left side, sternum, and right ankle. She was subsequently taken by ambulance to an emergency room, where she underwent open reduction and internal fixation surgery on her right ankle the following day, on July 23, 2011. Martin remained in the hospital for six days and spent an additional eight days at a skilled nursing facility. She underwent minor surgery to remove a screw from her ankle on July 27, 2011, and had no further treatment, opting to perform her own physical therapy at home. Martin was able to return to work full-time, without restriction, only 14 weeks after the accident and made an excellent recovery. However, she testified that she continues to suffer some ankle pain and stiffness after physical activity. The plaintiff’s treating orthopedic surgeon testified via video deposition that Martin can expect more ankle symptoms in the future due to the likeliness of accelerated arthritis of the right ankle joint. Thus, Martin sought recovery of $147,057.69 in stipulated past medical costs and $30,867.20 in stipulated past lost earnings. She also sought recovery of damages for her past and future pain and suffering.