Hearsay in its everyday usage refers to a statement repeated from what one has heard from a third party, without any attempt to verify its validity. Gossip is a type of hearsay. Literally the term comes from "hear it said," which is inherently unreliable as to the truth what was supposedly said.
Hearsay also has a specific usage in the legal profession: hearsay is an out-of-court statement, by someone other than the witness testifying, admitted to prove the truth of what was asserted in the statement. The concept is best thought of as codifying the unreliability of secondary or tertiary knowledge.
Explained another way, hearsay is evidence presented by a witness who did not see or hear the incident in question but heard about it from someone else.
Hearsay is typically excluded from legal proceedings due to its lack of reliability for reasons including the following:
- the speaker of the hearsay may have been uninformed
- the speaker of the hearsay may have been lying, without providing the court an attempt to check against the alleged declarant
There are limited exceptions that do allow the admission of hearsay as evidence when special circumstances make the hearsay more reliable than usual. These exceptions include, for example:
- certain prior statements by a witness (F.R.Evid. 801(d)(1) - not considered to be hearsay at all)
- admissions against a party's own interest (in the federal rules, F.R.Evid. 801(d)(2) this is not considered hearsay at all)
- records habitually kept by a person with knowledge of a matter (the "business records exception")
- dying words
- things said in the midst of an occurance - the res gestae
- statements in learned treatises, provided that the statements are read by an expert on the witness stand
Hearsay only refers to statements offered to prove the truth of the matter asserted. It does not apply or limit use of testimony about hearing a statement, if not offered to prove the truth of the matter asserted. For example, Bob hearing someone tell him that Richard had stolen his car is not evidence that Richard stole Bob's car, but it can be evidence that Bob believed his car had been stolen by Richard (and was therefore angry with Richard). This exception is generally called the "State of Mind" rule.