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Summary of Evidence Rules: Overview

The outcome of a case often depends on what evidence is admissible. While rules of evidence and case law provide guidance on admissible evidence, attorneys know that judges have wide discretion in allowing evidence. A well-timed objection can throw a wrench in the opposing party's case or get a jury on your side. Failing to raise the right timely objection to evidence can preclude you from appealing after a loss.

While few other matters are as important in litigation, evidentiary rules are complex. Most trial errors involve questions of admissibility. This is understandable, as each state has its own rules of evidence that may vary from federal rules and the rules of other states. Caselaw can further refine allowable evidence and testimony (such as the Daubert trilogy). Layers of complexity exist for every rule.

The following is a bird's-eye view of rules of evidence, along with links to further information, for anyone looking to brush up on rules of evidence. This summary cites to the Federal Rules of Evidence (FRE) for the sake of simplicity. 

Rules of Evidence Basics

Evidence is used at the summary judgment and trial stages of a case. Evidence can be used for a limited purpose. A jury can be instructed to only use evidence to help determine a single fact and not draw inferences to other facts, for example. A jury can also be instructed to apply evidence to only one party to a case in certain circumstances.

Both direct evidence and circumstantial evidence are admissible in court. Direct evidence proves a fact on its own, while circumstantial evidence requires the fact-finder to infer a fact from the evidence. An example of direct evidence is seeing Johnny steal a candy bar. Circumstantial evidence is seeing Johnny near the store after the candy bar was stolen with chocolate on his face.

Both direct and circumstantial evidence that is relevant, can be authenticated, and is not otherwise excluded by a rule is admissible.

Types of Evidence

There are four general types of evidence:

  • Real (or tangible) evidence is directly involved in the case, such as the gun involved in the murder.
  • Demonstrative evidence helps to clarify or assist in witness testimony. A map showing the scene of the accident is an example of this.
  • Documentary evidence can also be a type of real evidence, such as a contract. This includes electronic and digital evidence, as well.
  • Testimonial evidence is what a competent witness says in court.

Each type of evidence has its own rules for establishing relevance and being authenticated, two requirements for admissibility.

Relevant Evidence

For evidence to be relevant, there must be some logical connection, even if just a tenuous one, to the evidence and the fact trying to be proved. An item of evidence can be admissible even if it does not prove or disprove something on its own.

As the Federal Rules of Evidence puts it, evidence is relevant if:

  • “it has any tendency to make a fact more or less probable than it would be without the evidence; and
  • the fact is of consequence in determining the action" (FRE 4.01).

In other words, relevant evidence only needs to have “any tendency" that can help determine the probability of a fact. This means even weak evidence can be relevant. It is up to the trier of fact to weigh evidence and determine whether it proves anything or not. 

Irrelevant evidence is inadmissible. Relevant evidence is admissible unless there is a rule excluding it.


In addition to being relevant, admissible evidence must be authenticated. To authenticate evidence is to show that the evidence is what it is supposed to be. Attorneys can authenticate evidence through:

  • Witness testimony
  • Stipulating the evidence is authentic with opposing counsel
  • A request for admission, usually issued during discovery, in which one party asks the other to admit or deny that an item of evidence is authentic

Typically, tangible and documentary evidence is authenticated through testimony. Asking a witness in court, “Is this the contract you entered into?" is one example. Tangible evidence can also be authenticated by establishing a chain of custody, but this is much more burdensome.

Some evidence is self-authenticating. Examples of self-authenticating evidence under FRE 902 include certified copies of public records, official publications, and certified data copied from an electronic device.

Judges can also note facts (although only some types of facts, like filing dates and geographical boundaries) that do not then have to be authenticated. These are called judicially noticed facts.

Lay Witness Testimony

Lay witness testimony involves an individual testifying in court about facts or opinions to which they have personal knowledge (FRE 701). The old prohibition on lay witnesses being able to only testify to “facts" proved untenable.

Lay witness testimony is admissible if:

  • It's based on the witness' perception
  • It is not based on technical knowledge (i.e. it is not expert witness testimony)
  • The witness is competent
  • The witness can remember and communicate what they perceived

Of course, simply because a witness is allowed to testify does not mean everything they say is admissible. Numerous objections to witness testimony exist. For example, hearsay is not admissible. More on hearsay later. In addition, attorneys generally cannot ask leading questions on direct examination, but can on cross-examination. A leading question is one in which the attorney begs an answer in the question.

Attorneys also cannot do the opposite, which is ask a narrative question. A narrative question is one which is so general it allows the witness to ramble on, not allowing opposing counsel to object to potentially inadmissible testimony. Judges have a lot of leeway for determining whether a question is leading or narrative. Interpreted broadly, most questions could be considered leading or narrative.

A witness can also be impeached at any time, meaning their credibility can be questioned. See the character evidence section for more information on this.

A witness may also violate the best evidence rule.

Other examples of common objections in witness testimony include:

  • Lacks personal knowledge/speculative: The witness is being asked to give an opinion to which the witness does not have firsthand knowledge.
  • Lacks foundation: The information hasnot been authenticated. For example, asking what the witness saw before establishing that the witness was at the scene.
  • Ambiguous/misleading: The testimony is confusing or open to interpretation.
  • Non-responsive: Meaning, the witness did not answer the question.
  • Violates the parol evidence ruleThe evidence is offered to contradict or modify clear writing.
  • Repetitive: The question was already asked and answered.

Expert Witness Testimony

Expert testimony is the opinion of an expert regarding a fact. Unlike lay witness testimony, an expert witness can testify regarding a fact to which they do not have first-hand knowledge. For example, a neurosurgeon can testify about the effect of brain damage on an accident victim even if they did not personally operate on the victim.

Expert witness testimony is admissible if:

  • The court qualifies the witness as an expert
  • The expert's knowledge is helpful to the trier of fact to understand evidence
  • It is based on sufficient facts or data using reliable methods

Many of the same objections to lay witness testimony applies to expert testimony, as well.

The U.S. Supreme Court set the standard for expert testimony admissibility in federal courts in the Daubert trilogy of cases.

Character Evidence

Typically, evidence of someone's character is not admissible to prove that a person acted in accordance with their character or trait. In other words, evidence that a person stole before is not admissible to prove that they stole this time. This is true whether a person's character is relevant or not. Just because Johnny stole M&Ms before doesn't mean he stole the Snickers Bar this time.

The exception is in witness testimony. Counsel can use character evidence to support or attack the credibility of a witness. Character evidence can also be used where it is directly an issue in a case. For example, if one party is suing for defamation, opposing counsel can introduce evidence that the reputation of the suing party was already in shambles and so no damage was done.

Finally, under FRE 404, character evidence can be used to show a person's

  • Motive
  • Knowledge
  • Intent
  • Identity

Habit evidence is separate from character evidence. Habit evidence can be used to show a person's routine led to a response on a specific occasion. For example, introducing evidence that person always had two beers after work at happy hour can be used as evidence that person had two beers after work on a specific date.

The difference between character evidence and habit evidence can be difficult to determine. Typically, courts look at the number of instances and the uniformity of a person's behavior to label it as character evidence or habit evidence.

Best Evidence Rule

The best evidence rule (FRE 1002) requires that an original writing or record be used, unless there is a good reason for it.

Legitimate reasons to not use an original copy include:

  • It is disputed what the original copy is
  • The circumstances would make it unfair
  • The original is not available


Hearsay is an out-of-court statement offered to prove the truth of the matter asserted in the statement. “Bob told me back in June that Johnny stole that candy bar" is hearsay, because it occurred out of court and is being offered to prove that Johnny stole a candy bar. Hearsay is generally not admissible, but there are numerous exceptions to this rule. There are also exceptions to those exceptions. For the purposes of this summary, note that common hearsay exceptions include:

  • A present sense impression, which is made right after the witness perceived it
  • An excited utterance which is a statement made while still under the stress or duress of a startling moment.
  • Then-existing mental, emotional, or physical condition, for example“he looked upset"
  • A medical diagnosis or treatment
  • A recorded recollection

There are only 22 more exceptions, in addition to admissible nonhearsay rules.

Attorney-Client Privilege and Work Product

Confidential communications made between an attorney and their client regarding legal advice is protected. This could include actual legal advice, requests for legal advice, and facts provided by the client to the attorney made for the purpose of obtaining legal advice.

The Work Product doctrine protects tangible and documentary evidence made in preparation for litigation.

Master the Basics

We've only scratched the surface of federal rules of evidence. However, a solid understanding of the basics goes a long way toward capably handling most questions of admissibility. This, in turn, will allow you to confidently research more niche areas of the evidentiary rules, and, importantly, allow you to focus both on the substance of your legal matter and on its presentation.

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