Territory of Arizona v. Follett

In this case the trial court gave the following instruction: “In considering the question of guilt or innocence the jury had the right, and it is its duty, to examine carefully into the credibility of the witnesses; and in investigating the question of credibility the jury has a right to take into consideration the motives of witnesses so far as *92the position or testimony of a witness discloses any motive, and if the jury finds that any witness has'sworn falsely on a material fact they have the right to disregard his whole testimony, except so far as the testimony of such witness be…