Competence is the legal ability to give evidence. It is obvious that every compellable witness is a competent witness because the court will not compel anyone to give evidence if he is incompetent to do so. On the other hand it is not every competent witness that is compellable. Any compellable witness who refuses to give evidence can be punished for contempt of court. Yet, a compellable witness may be excused from answering certain questions.
For a person to be called as witness he must be someone considered in law as fit and proper before his testimony can be received in evidence. Thus, he must be a competent person. The general rule is that in criminal and civil proceedings, every person is presumed to be competent to give evidence.
According to s175(1) of the Evidence Act 2011, “All persons shall be competent to testify unless the court considers that they are prevented from understanding the questions put to them or from giving rational answers to those questions by reason of tender years ,extreme old age, disease, whether of body or mind, or any other cause of the same kind.”
Thus the test for every potential witness is his/her ability to understand questions put to him and to provide rational answers thereto. It is clear that by the foregoing provisions of the law, the court presumes every potential witness before it as a competent witness even though this presumption can be rebutted. This implies that the court does not, immediately a potential witness appears, begin to put questions to test his competency. However, this particular function of the court arises if the court observes that the potential witness before it may not be a competent one.
From the above provision, one could infer that there is competence of four categories of witnesses viz:
Persons suffering from disease; and
Mentally unsound persons.
Objections may be raised against the competence of a witness (to testify in a case) on the ground that:
1. The witness is unable to express himself in any way which the court can be made to understand.
2. The witness is incapable of telling the truth. This is usually on the ground on which the competency of persons of tender age is challenged. When such objection is raised, the court takes step to ascertain whether or not the person concerned does in fact appreciate the duty of telling the truth.
3. The witness lacks personal knowledge of the matter in respect of which he is called to testify. For instance, the native law and custom of a particular area –section 59 of the Evidence Act 2011.
4. The witness is not qualified in the special field where his opinion testimony is required as an expert.
However, the test of competence is the ability of the witness to understand questions asked and give rational answers to them. In Asuquo Eyo Okon v. The State (1988) ANLR 173 at 186, Agbaje JSC said, “Since all persons are competent to testify, until the competence of a witness to testify is challenged for any of the reasons stated in the section there is in my view no obligation on the court to determine the competence of a witness to testify”.
It is necessary here to point out that once a person who is not a party to the suit is a competent witness, the mere fact that he has listened to a part or all the evidence that has been given in the case does not make him cease to be a competent witness. The only effect the court will attach on his evidence is the weight that the court will attach on his evidence as was held in Falaju v Amosu (1983) 2 SCNJ 209.
A compellable witness on the other hand is not necessarily obliged to answer every question or to give evidence of every fact or issue for example, he may be able to claim privilege or he may be disallowed for giving evidence under the provision of the law.
While every man is a competent witness not every man is a compellable witness. On the other hand, once a person is compellable a fortiori such a person is presumed a competent witness for one cannot be compellable if he is first and foremost not competent though one can be competent without being compellable. Thus a witness may be competent without being compellable. However every compellable witness must be competent to give evidence.
Compellability is the obligation imposed on a competent person to attend or give evidence in court. It should be noted that every compellable witness is competent but not every competent witness is compellable.
There are however situations where competent and compellable witnesses are not necessarily obliged to answer every question or give evidence of every fact or issue for example where the witness claims privilege or is disallowed under the provision of the law as enunciated in the Evidence Act.
B.E Ewulum and O. Mbanugo (2015) Competence and Compellability Under the Evidence Act of Nigeria.
Competenceand Compellability of Witnesses. http://www.lawrepository.com.ng/2014/10/competence-and-compellability-of-witness.html
T.A Aguda. The Nigerian Law of Evidence.
Fagbemi S.A on The Nigerian Law of Evidence.
The Evidence Act 2011