VI. WITNESSES' COMPETENCY. A witness is not competent to testify until he has taken oath to testify truly. At common law an atheist or other unbeliever in the Christian religion was not a Mal peteut witness, because it was believed that he would not feel constrained by his oath to test ify truly. At the present time a witness is generally allowed to testify on his oath or affirmation, no particular religious belief being requisite. A child is a competent witness if old enough to un derstand the nature and obligation of an oath, and an insane person may testify upon a matter concerning which his understanding is not af fected by his insanity. At common law one con victed of a felony within the jurisdiction was in competent as a witness unless pardoned. In most jurisdictions such a conviction now affects the credibility only, and not the competency of the witness. At common law a party to an action was not a competent witness in his own behalf, nor was one a competent witness if directly interested in the controversy. This disability has been generally removed by statute. Nor could either the husband or wife testify for or against the other at common law. This dis ability has been removed to some extent by stat ute in most jurisdictions, but not generally so as to permit testimony as to confidential com munications between husband and wife.
It was the policy of the common law to pro tect the witness from being compelled to incrimi nate himself. He is therefore privileged from giving any testimony which tends to incriminate him or to subject, him to a penalty or forfeiture. If the witness does not claim his privilege, his testimony is competent and subject to the usual rules of the law of evidence. Having once fairly waived his privilege, he must testify fully. Thus a defendant in a criminal trial is privileged from being compelled to testify; but having offered to testify in his own behalf, he must answer proper questions directed to him on cross-examination. At common law, also, an attorney and client were privileged from testifying as to any confidential communication between them. By statute this privilege Las in most jurisdictions been extended to persons standing in other confidential rela tionships, e.g. physician and patient. clen>yman
or priest and layman, and in some jurisdictions, notably New York, attorneys. physicians, and clergymen are not competent to testify as to con fidential communications received by them in their professional capacity. 'Upon the similar ground of public policy, a party is privileged from testifying as to his efforts or willingness to compromise the matter in controversy, and it is probable that the President of the United States and the llovernors of States are privileged from appearing as witnesses under any circumstances.
VII. ExAmIN.vrioN or Witnesses may be classified as favorable or opposing. A favorable witness is one Ca I It'd by a party to tes tify in support of his contention in the contro versy, and an opposing witness is one called by the other party to the controversy to testify in his behalf. The favorable witness on one side is therefore the opposing witness of the other. As a general rule one is not allowed to ask his own (or favorable) witness leading ques tions, that is, questions which by their form indicate the answer desired. The extent to which leading questions may be asked, however. rests in the discretion of the trial judge, and should the prove hostile leading questions may be asked. One may not impeach the credibility of his own witness; that is, he is not allowed to in troduce testimony to show generally that the wit ness is not worthy of belief. Ile may, however, contradict the testimony of the witness by other witnesses for the purpose of showing the truth as to a fact about which the first witness has testified. At the close of the direct examination, or the examination of a favorable witness, counsel for the other side may e•oss-examine, that is, may examine him as an opposing witness. rin cross-examinations it is permissible to ask lead ing questions. The cross-examiner may also at tack the credibility of the witness, and for that purpose may ask questions not otherwise rele vant. The witness, however, may refuse to an swer questions of this class which tend to incrimi nate or degrade him. The credibility of an op posing witness may also be attacked by intro ducing testimony to show that lie is generally unworthy of belief.