Article 137 — ; - Form of questions put in examination-in-chief

(I) Questions put in examination-in-chief shall only relate to facts which are relevant to the issues to be decided and to such facts only of which the witness has direct or indirect knowledge. (2) No leading question shall be put to a witness without the permission of the accused or his advocate or the public prosecutor, as the case may be. (3) Questions put in cross-examination shall tend to show to the court what is erroneous, doubtful or untrue in the answers given in examination-in-chief. Leading questions may be to a witness in cross-examination.