Definition
Books of science are published scientific, medical, or technical works — treatises, reference texts, or authoritative compilations — offered in legal proceedings for the truth of the scientific propositions they contain. The evidentiary question they raise is whether such works may be introduced directly as substantive evidence before a jury, or whether their use is limited to other purposes, such as impeaching expert witnesses.
At common law, the general rule was exclusionary: books of science, however authoritative, were inadmissible as independent proof of the facts or opinions they stated. The primary objection was that the authors could not be cross-examined, and that jurors might give undue weight to printed authority without the mediating judgment of a live expert. Under this traditional framework, a party could not simply hand the jury a medical treatise and ask them to accept its conclusions.
The recognized exception was impeachment: if an expert witness based an opinion on or acknowledged the authority of a particular work, opposing counsel could use that work to challenge or contradict the expert's testimony. The book did not come in for its truth — it came in to test the reliability of the expert who vouched for it.
Common Confusion
Books of science should not be confused with learned treatises as a hearsay exception, a distinct doctrine that developed later under modern evidence codes. Under Federal Rule of Evidence 803(18) and its state equivalents, a published treatise, periodical, or pamphlet may be admitted as substantive evidence — not merely for impeachment — if established as reliable authority and relied upon by or called to the attention of an expert witness on cross-examination. The Bouvier-era rule described under "books of science" reflects the pre-codification common law position, which was substantially more restrictive. Researchers encountering the term in historical sources should not assume modern learned treatise doctrine applies.
Why It Matters in Research
This term is principally a period marker. It signals common law evidentiary doctrine from the nineteenth and early twentieth centuries, before the Federal Rules of Evidence (1975) and analogous state codifications transformed the treatment of expert-related material. When encountered in historical case law, treatises, or pleadings, it tells the researcher that the operative rule was the strict exclusionary common law position — not the modern learned treatise exception.
Two research traps arise. First, cases decided under the "books of science" framework may have excluded evidence that would be freely admissible today under Rule 803(18) or equivalent state rules. Citing those cases for modern evidentiary propositions risks applying obsolete doctrine. Second, the partial exception for impeachment purposes survived into modern practice but was absorbed and reframed within the learned treatise exception and expert cross-examination rules. The terminology shifted even where the underlying logic partially persisted.
Researchers working in medical malpractice history, the history of expert testimony, or the development of scientific evidence doctrine will find this term at the center of a long-running tension between the common law's distrust of unsworn printed authority and the practical need to bring specialized knowledge before courts. The trajectory from "books of science" to "learned treatises" is one of the cleaner doctrinal evolution lines available for tracing how courts adapted to increasingly technical litigation.
Historical Dictionary Support
Bouvier's Law Dictionary states the exclusionary rule plainly: scientific books, even of received authority, are not admissible in evidence before a jury. Bouvier cites Greenleaf's Evidence (§ 440a) — the standard nineteenth-century American evidence treatise — as authority for this position, alongside a cluster of Massachusetts and Illinois case citations. The narrow exception Bouvier identifies — permitting use of a scientific work to contradict an expert who bases an opinion on it — is consistent with the general common law pattern documented in Greenleaf and in the case law of the period.
No other historical dictionaries in the current source set address this term. Bouvier's entry, though brief and truncated in the available text, accurately reflects the dominant American common law position of its era. What Bouvier's treatment does not address, and could not, is the subsequent doctrinal shift: the gradual recognition in the twentieth century that the strict exclusionary rule produced absurd results in technical litigation, and the eventual codification of the learned treatise exception as substantive — not merely impeachment — evidence.