The most challenging element to prove in a medical malpractice case is often causation. This involves demonstrating that the healthcare provider's specific action or inaction directly caused the patient's harm. Establishing a standard of care or showing that the standard was breached can be done through expert testimony about what a competent healthcare provider would have done under similar circumstances. Proving causation, on the other hand, requires a clear link between the provider's negligence and the injury suffered.