People v. Berkman, 139 N.E. 91 (Ill. 1923)

He was then asked to examine the Colt automatic 32 aforesaid, and gave it as his opinion that the bullet introduced in evidence was fired from the Colt automatic revolver in evidence. He even stated positively that he knew that that bullet came out of the barrel of that revolver, because the rifling marks on the bullet fitted into the rifling of the revolver in question, and that the markings on that particular bullet were peculiar, because they came clear up on the steel of the bullet. There is no evidence in the case, by which this officer claims to be an expert, that shows that he knew anything about how Colt automatic revolvers are made and how they are rifled. There is no testimony in the record showing that the revolver in question was rifled in a manner different from all others of its model, and we feel very sure that no such evidence could be produced. The evidence of this officer is clearly absurd, besides not being based upon any known rule that would make it admissible. If the real facts were brought out, it would undoubtedly show that all Colt revolvers of the same model and of the same caliber are rifled precisely in the same manner, and the statement that one can know that a certain bullet was fired out of a 32-caliber revolver, when there are hundreds *501 and perhaps thousands of others rified in precisely the same manner and of precisely the same character, is preposterous

If it were possible in this case to determine whether or not the bullet in question was fired from the gun in question, it must have been by the peculiar rifling or condition of the gun that made what are called the peculiar markings on the bullet aforesaid. If any facts pertaining to the gun and its rifling existed by which such fact could be known, it would have been proper for the witness to have stated such facts and let the jury draw their own conclusions. Under the testimony of this witness, if allowable, the court would have had no alternative, except to admit the gun in evidence, if the proof had been positive that the bullet in question was the bullet cut out of Rahn’s back by the physician. It is stated by Jones on Evidence, in the sections above cited, that the general rule that facts, and *502 not conclusions, should be stated, tends to prevent fraud and perjury, and is one of the strongest safeguards of personal liberty and private rights, and that whenever it is doubtful whether a case falls under the rule, or under one of its exceptions, the wise course is to place it under the rule.