Life policies are legal contracts and the terms of each contract describe the limitations of the insured events. Often, specific exclusions written into the contract limit the liability of the insurer; common examples include claims relating to suicide, fraud, war, riot, and civil commotion. Difficulties may arise where an event is not clearly defined, for example: the insured knowingly incurred a risk by consenting to an experimental medical procedure or by taking medication resulting in injury or death.