Negligence is doing something that a person using reasonable care would not do or not doing something that a person reasonable care would do. Reasonable care is the skill or attention a reasonable person would use under similar circumstances. Accordingly, a determination whether or not somebody was negligent can come down to something as simple as whether or not they went through a red light - behavior a reasonable person under similar circumstances would not do - or deciding how reasonable people would act under similar circumstances as if the behavior was controlled by traffic signal. For instance, in a medical malpractice case the question is, "Did the behavior that caused an injury appear to be the result of somebody going through a "medical malpractice red light" or was it just the risk of the procedure?" Negligence is therefore a common sense concept that relies on an understanding of how reasonable people would behave.