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|Part of the common law series|
|Types of evidence|
|Hearsay and exceptions|
|Other common law areas|
Under the common law, such evidence was at one time considered hearsay - a statement made out of court being introduced to prove the truth of the statement - and was not admissible except to rebut the testimony of an opposing expert witness. There were four ways to introduce such evidence:
- Adduce testimony that the opposing expert witness actually used that text to reach his conclusions;
- Adduce testimony by the opposing expert admitting that the text is an authority in the field;
- Have a friendly expert witness testifying against the opposing expert witness attest to the authoritativeness of the text.
- Have the judge take judicial notice of the text, if it is sufficiently notable that the average person would know that it is an authority ( ).
Under the Federal Rules of Evidence 803 (18), either party can introduce a learned treatise as evidence, irrespective of whether it is being used to rebut the opposing party. Such texts are now considered an exception to hearsay, with two limitations:
- For the learned treatise to be introduced, there must be an expert witness on the stand;
- Like a recorded recollection, the actual learned treatise does not go to the jury, but instead comes into evidence only by being read to the jury.