In United States and Canadian law, competence concerns the mental capacity of an individual to participate in legal proceedings or transactions, and the mental condition a person must have to be responsible for his or her decisions or acts. Competence is an attribute that is decision specific. Depending on various factors which typically revolve around mental function integrity, an individual may or may not be competent to make a particular medical decision, a particular contractual agreement, to execute an effective deed to real property, or to execute a will having certain terms.
Depending on the state, a guardian or conservator may be appointed by a court for a person who satisfies the state's tests for general incompetence, and the guardian or conservator exercises the incompetent's rights for the incompetent. Defendants who do not possess sufficient "competence" are usually excluded from criminal prosecution, while witnesses found not to possess requisite competence cannot testify. The English equivalent is fitness to plead.
Character evidence is a term used in the law of evidence to describe any testimony or document submitted for the purpose of proving that a person acted in a particular way on a particular occasion based on the character or disposition of that person. In the United States, Federal Rule of Evidence 404 maps out its permissible and prohibited uses in trials. Three factors typically determine the admissibility of character evidence:
1. the purpose the character evidence is being used for.
2. the form in which the character evidence is offered.
3. the type of proceeding (civil or criminal) in which the character evidence is offered.
Habit evidence is a term used in the law of evidence in the United States to describe any evidence submitted for the purpose of proving that a person acted in a particular way on a particular occasion based on that person's tendency to reflexively respond to a particular situation in a particular way.
Habit evidence must be distinguished from character evidence, which seeks to show that a person behaved in a particular way on a particular occasion based on that person's prior bad acts, or based on the opinion of a witness, or based on that person's reputation in the community. Such character evidence is generally inadmissible.
In the law of evidence, similar fact evidence (or the similar fact principle) establishes the conditions under which factual evidence of past misconduct of the accused can be admitted at trial for the purpose of inferring that the accused committed the misconduct at issue.
