The term "competency" refers to the minimal qualifications someone must have to be a witness. In order to be a witness, a person other than an expert (experts are a special case discussed later in the course) must meet seven basic requirements.
1) Take some kind of oath to tell the truth.
2) Have a functioning memory and ability to communicate.
3) Not already be involved in the trial as a judge or juror
4) Not be one of the attorneys in the case
5) Not be disqualified by the Dead Man's Rule.
6) Be old enough to be able to testify at least as intelligently as Glen Beck.
7) Have actually witnessed something.
Not all these requirements are of equal importance. The first three never come up. No judge is going to let a witness take the stand without administering the
oath. No attorney in his or her right mind is going to intentionally call a witness who has no memory or cannot communicate, and if they do, you're not going
to object to it. No attorney is going to call the presiding judge or a juror as a witness
The fourth is a lot of fun at the pretrial stage -- Ethical rules prohibit a lawyer from serving simultaneously as a witness and an advocate. You subpoena the other side's lawyer to be a witness and then file a motion to disqualify him or her from representing your opponent because of the witness/advocate rule. However, it's not relevant at the trial stage.
That leaves three competency issues --
5) The dead man's statutes are state laws so obscure they are a favorite of bar examiners. Basically, a live person cannot claim that a dead person owed them money if there's no written evidence of the debt. Otherwise, an estate would soon be depleted by phony claims. There are dozens of exceptions, qualifications, twists and turns. If you are interested in seeing the Indiana Dead Man's Statutes, click here .
6) Whether a young child can understand the obligation to tell the truth and can communicate in some sensible way. The usual rule is that a child is competent if the child "is sufficiently intelligent to observe, recollect and narrate the facts and has a moral sense of obligation to tell the truth." This means that when small children are involved, the judge and attorneys will have to question the child about his or her ability to accurately describe what the child has seen, and about whether the child understands the difference between true and false, and will tell the truth.
7) And most importantly -- does the witness have personal knowledge of all the facts to which the witness testifies. Along with relevancy, this is one of the two most fundamental rules of evidence. A witness may only testify to matters within their personal knowledge. Rule 602 says "a witness may testify to a matter only if evidence is introduced sufficient to support a finding that the witness has personal knowledge of the matter." That means it is the obligation of the person calling a witness to establish by preliminary questions that the witness has personal knowledge of something relevant.
8) The difficulty is figuring out whether a sufficient foundation has been laid. The principles are:
a) Personal knowledge is acquired through the senses -- the witness must have seen, heard, felt, tasted or smelled something.
b) Any credible evidence will establish the foundation, usually having the witness testify "I was there and I saw it."
c) When a witness is testifying about events, the foundation is easy ("I saw it") but when a witness testifies to meanings, intentions, feelings, customs, and
other intangible things, the foundation is hard because although you cannot see into someone else's mind, you can certainly "see" when your mother is
upset.