The most significant factor in personal injury cases is negligence, which means a person did not act carefully or reasonably and caused someone else's injury. However, proving someone's negligence is easier said than done. You must provide evidence that: The other party had a duty to act reasonably to prevent injury under the circumstances They failed to abide by their duty Their failure resulted in your harm You incurred damages due to your injuries Proving negligence is the key to a personal injury lawsuit.