The ability to stand trial refers to a person's general mental capacity for a defendant in a criminal case to understand what is going on in their criminal case. In order for a person to be deemed to have the ability to stand trial, they must understand the consequences or the legal proceeding and must be able to effectively cooperate with their attorney.
The ability to stand trial came about in the United States due to the ethical considerations of a person going through a criminal trial as the alleged criminal. The three major components of a person's ability to stand trial is their competence to proceed through trial, their competence to be executed, and their competence to plead guilty in the case. A court in the United States will try to remedy the situation when a defendant is not competent. For example, a person cannot be put to death if they cannot understand what it means to be sentenced to death.