Intellectual Even in common occurrences intelligence is required to understand what actually takes place. Memory must be accurate and retentive to recall the facts. Power of expression is needed to report them accurately and faithfully. Power of interpretation must accompany perception. Dull people see ghosts, and stupid people hear death bells and other warnings. Simple-minded people report their vain imaginings for things seen or heard or remembered. Others leave gaps in essential matters, either from lack of perception or from lapses of memory. Indefiniteness in the meaning of words and looseness in the use of expressions, render testimony unconvincing. An object is light colored or dark, near by or distant, large or small, strange or familiar, to different persons. tion. A witness's character as well as his reputation affects his credibility. The testimony of a criminal is worthy of little credit, however keen his power of observation and fluent his power of expression. A man Character and Reputa- who is known to have lied once, is doubted on future occasions though he speak the truth; and the reputation of an habitual liar may render his testimony worse than worthless. The value of character as well as of intellectual qualities in a witness, is well shown in that part of Webster's speech,1 in which he compares the respective claims of Colman and N. P. Knapp to credibility. Effect of The value of testimony is modified by the beliefs of a witness. If he believes in the return of disembodied spirits, he may testify to having seen a ghost, when he has seen only a white ani1 Pages 279, 330. mal or a stump or a sign post, made white by the light of the moon. To him, the moaning of the wind about an angle, the hum of a telegraph wire, the rubbing of a branch against a window pane, may seem the voice of the dead. His belief is liable to keep him in such a mental condition as to incapacitate him for either accurate observation or just interpretation of phenomena presented. One who believes in supernatural warnings of coming disaster, will be all the more susceptible to illusive appearances; and his report will be so much the less trustworthy. Cases in which illusion is due to beliefs, are to be distinguished from those which are the result of an overworked or overstimulated imagination. Sir Walter Scott is said to have seen a phantom of the dead Byron.1 Luther's seeing the devil and Single hurling an inkbottle at him, is an historic incident. These illusions, however, would hardly affect the testimony of these men on any matters whatever. Illusions. Trustworthy Trustworthy memory will recall three things: (1) that something did really happen; (2) that it happened in the way the witness now thinks; (3) that it happened when and where it now appears to have happened. The witness's memory cannot be Memory. called reliable if he is indefinite on any of these points. There are three corresponding illusions of which even an honest witness may be the victim: (1) false recollections to which no real events correspond; (2) recollections misrepresenting the manner of happening; (3) recollections omitting or falsifying the date and time of the happening. 1 Sully, Musions, 121. Interested Following the general experience of mankind, the common law rejects the testimony (1) of parties to the record, (2) of persons deficient in understanding, (3) of persons insensible to the obligations of an oath, (4) of persons pecuniarily interested in the matter in issue. It presumes the testimony of an accomplice to be worthy of but little credit. Self-interest, whether of a pecuniary, personal or professional nature, may conflict with the presumption that a witness will tell the exact truth on a particular occasion. Testimony to the genuineness of a will under which the witness inherits; testimony to the service rendered to the country by the political party in which the witness is a candidate for office; testimony to the efficacy of a medicine patented by the witness, or the superiority of the school of medicine in which the witness is a practitioner; testimonials as to the scholarship of students whom the witness has helped to educate, and in whose appointment he is interested, are to be taken with a degree of allowance. A woolgrower might be too much interested in the tariff, a miner, in silver, a Baconizer, in his theory of the authorship of Shakespeare's plays, to give trustworthy evidence upon facts connected with those matters. In some cases the validity of testimony depends especially on the intellectual character and equipment of the witness. While his honesty and desire to tell the truth may not vary, his thorough mastery of Experts. the subject, acquired by long study and experiment is of special importance. "On questions of science, art, trade or others of like kind, persons of skill, sometimes called experts, are called not only to testify to facts, but to give their opinions in evidence. Thus the opinions of physicians are constantly sought as to the cause of a disease or death or the consequences of wounds, or as to other circumstances best known to those skilled in the medical profession. But such evidence is usually admitted only on facts proved, not on the general merits of the case." The statement, often made, that ordinary witnesses give testimony as to facts only, while experts testify to conclusions from facts proved, is hardly correct. The non-expert gives the results of processes of reasoning familiar to every-day life; the expert gives the results of a process of reasoning which can be mastered only by special scientists. Thus, in disputed matters of navigation, experts may prove general usage. A physician may testify as to injuries to the eye, as to the effect of arsenic, as to the sanity or insanity of a patient; a chemist may be called to testify as to whether certain stains are blood, as to the effect of certain poisons on the human system, as to the effect of a certain powder in removing ink marks; a surgeon may testify as to the cause, probable effects and nature of wounds; a botanist, as to the character and relations of different kinds of wood; a lawyer, as to court practice and customary fees; builders and carpenters, as to the safety of structures, and so on. But the specialty within which such evidence is given, must be exclusively that in which the expert witness is skilled. The testimony of experts is to be carefully scrutinized. This necessity is recognized in the general employment of experts on both sides of a case. Not only a possible interest in one of the parties to the suit, and Care in inevitable friendliness toward the source of compensation, but his devotion to some theory, his jealousy of his reputation as a scientist, lawyer, or physician, his natural desire that his side of the case be established, all this, granting him to be honest, casts suspicion on the accuracy of an expert's testimony. "When expert testimony was first introduced, it was regarded with great respect. An expert, when called as a witness, was viewed as the representative of the science of which he was a professor, giving impartially its conclusions. Two conditions have combined to produce a material change in this relation. In the first place, it has been discovered that no expert, no matter how learned and incorrupt, speaks for his science as a whole. Few specialties are so small as not to be torn by factions; and often, the smaller the specialty, the bitterer and more inflaming and distorting are the animosities by which these factions are possessed. Peculiarly is this the case in matters psychological, in which there is no hypothesis so monstrous that an expert cannot be found to swear to it, and to defend it with vehemence when off the stand. In the second place, the retaining of experts, by a fee portioned to the importance of this testimony, is now, in cases in which they are required, as customary as is retaining of lawyers. No court would take as authority the sworn statement of the law, given by counsel retained on a particular side, for the reason that the most highminded men are so swayed by an employment of this kind as to lose the power of impartial judgment; and so intense is this conviction that in every civilized community the reception by a judge of presents from suitors, visits him not only with disqualification but disgrace. Hence it is that, apart from the partisan temper more or less common to experts, their utterances, now that they have as a class, become the retained agents of parties, have lost all judicial authority, and are entitled only to the weight which a sound and cautious criticism would award to the testimony itself. In adjusting this criticism, a large |