Rules of Evidence


We can only cover both the federal and California law of evidence in a brief essay like this by a ruthless process of selection and compression. What we will cover can best be thought of as that essential kernel of the law of evidence that the trial lawyer must carry in his head.

Our task would be impossible but for two important facts. First, all of you have studied the law of evidence before, either in a course on evidence or in preparation for the bar exam. Accordingly, most of the rules presented will already be familiar to you. What we will do here is to try to review, organize, and reinforce that law so that you can apply it with confidence when you need it.

Second, most of the rules of evidence need not be covered here because they are either so obvious that you already know all you need to know about them or they apply only in limited circumstances. For example, we would surely be wasting our time if we indulged in an extended discussion of the rule that evidence should be construed to achieve the ends of justice, and others like it. This and many other rules only state the obvious and will not be covered here. Rules that apply only in limited circumstances include ones like those relating to the scope of cross examination of a plaintiff in a case of sexual assault, a juror’s incompetence to impeach his own verdict, and the proof of valuation of property. Evid. Code §§ 781, 1150, 810 et seq.; Fed. Rules Evid. 412, 606. You do not need to know those special rules unless you get a case where they apply. When that happens, it will be time enough to study them.

What is left after you eliminate all the rules that are obvious and all those that have only limited application are the rules that are used every day in ordinary cases and that are not trivial or obvious. These essential tools of survival must be thoroughly mastered. They will enable you to solve the vast majority of evidentiary problems that arise in preparing and trying your cases.

I do recommend, however, that you take the time to read whichever codification applies to your practice so you will know when you need to study one of the rules of limited application and so that you can gain confidence that there are not any gaps in your knowledge.



There are four traditional types of evidence:

  1. real,
  2. demonstrative,
  3. documentary, and
  4. testimonial.

Some rules of evidence apply to all four types and some apply only to some or one of them. First, we will cover general rules of admissibility that apply to all evidence. Then, we will cover foundational rules that relate to specific kinds of evidence. Finally, we will cover some special topics, like the form of examination, the hearsay rule, and the lay opinion rule, that frequently cause problems in the courtroom.


The basic prerequisites of admissibility are relevance, materiality, and competence. In general, if evidence is shown to be relevant, material, and competent, and is not barred by an exclusionary rule, it is admissible. Evid. Code § 351; Fed. Rules Evid. 402.

Evidence is relevant when it has any tendency in reason to make the fact that it is offered to prove or disprove either more or less probable. Evid. Code § 210; Fed. Rules Evid. 401. To be relevant, a particular item of evidence need not make the fact for which it is offered certain, or even more probable than not. All that is required is that it have some tendency to increase the likelihood of the fact for which it is offered. Weighing the evidence is for the finder of fact, and although a particular piece of evidence, standing by itself, may be weak, it will be admitted unless it is otherwise incompetent or it runs afoul of an exclusionary rule. For example, if the fact to be proved is that the defendant bit off the plaintiff’s nose in a fight, testimony by an eyewitness to the act would clearly be relevant, but so would testimony by a witness who heard the plaintiff and the defendant exchange angry words on the day before the fight, or even testimony by a witness who sold the defendant a disinfectant mouthwash shortly afterwards.

Evidence is material if it is offered to prove a fact that is at issue in the case. For example, if I offer the testimony of an eyewitness to prove that it was raining on the day of the signing of a contract, that evidence may be relevant to prove the fact for which it is offered, yet the fact that it was or was not raining may be immaterial to any of the issues in the case, which may turn entirely on whether one or both parties breached the contract.

The issues in the case are determined by the pleadings, any formal stipulations or admissions, and the applicable law. For example, if, in a case of breach of contract, the defendant has conceded that the plaintiff performed all his covenants, proof of that performance would no longer be material unless it were relevant to some other issue. Under both the California and federal rules, the concept of materiality is included in the concept of relevance. Evid. Code § 210; Fed. Rules Evid. 410.

Evidence is competent if the proof that is being offered meets certain traditional requirements of reliability. The preliminary showing that the evidence meets those tests, and any other prerequisites of admissibility, is called the foundational evidence. Evid. Code § 402, 403. When an objection is made that an answer to a question, a document, or a thing lacks a proper foundation, what the objector is really saying is that a showing of competence, or of another prerequisite of admissibility, has not yet been made. The modern trend in the law is to diminish the importance of the rules of competence by turning them into considerations of weight. See, e.g., Evid. Code § 700; Fed. Rules Evid. 601. The question of competence will be considered below for each category of evidence.

In general, if competent evidence is offered to prove a relevant and material fact, it is admissible even if it would have been improper to receive it for another purpose. Evid. Code § 355. For example, while evidence of prior bad acts is generally not admissible to show that a person acted similarly in the present case, it may be admissible to show motive, plan, intent, lack of mistake or, in federal court, to impeach a witness’s credibility. Evid. Code § 1101(b); Fed. Rules Evid. 404(b). When evidence is received for a limited purpose, the party who thinks a jury may make improper use of that evidence is entitled, upon his request, to a limiting instruction. Evid. Code § 355.

However, where the value of evidence for its proper purpose is slight and the likelihood that it will be used for an improper purpose by a finder of fact is great, a court may, in its discretion, exclude the evidence even though it would otherwise be admissible. Evid. Code § 352; Fed. Rules Evid. 403. In this situation, the probative value of the evidence is said to be outweighed by its prejudicial effect.

Prejudice means improper harm. The fact that evidence may be extremely harmful to one party’s case does not necessarily make it prejudicial. Courts also have discretion to exclude otherwise admissible evidence to prevent confusion, delay, waste of time, or the needless presentation of cumulative evidence. Evid. Code § 352; Fed. Rules Evid. 403.


Real evidence is a thing the existence or characteristics of which are relevant and material. It is usually a thing that was directly involved in some event in the case. The written contract upon which an action is based is real evidence both to prove its terms and that it was executed by the defendant. If it is written in a faltering and unsteady hand, it may also be relevant to show that the writer was under duress at the time of its execution. The bloody bloomers, the murder weapon, a crumpled automobile, the scene of an accident–all may be real evidence.

To be admissible, real evidence, like all evidence, must be relevant, material, and competent. Establishing these basic prerequisites, and any other special ones that may apply, is called laying a foundation. The relevance and materiality of real evidence are usually obvious. Its competence is established by showing that it really is what it is supposed to be. Proving that real or other evidence is what it purports to be is called authentication. Evid. Code § 1400; Fed. Rules Evid. 901.

Real evidence may be authenticated in three ways–by identification of a unique object, by identification of an object that has been made unique, and by establishing a chain of custody. You only have to be able to use one of these ways, though it is prudent to prepare to use an alternate method in case the court is not satisfied with the one you have chosen.

  • The easiest and usually the least troublesome way to authenticate real evidence is by the testimony of a witness who can identify a unique object in court. For example, the curator of a museum may be able to testify that he is familiar with, say, Picasso’s “Dames de Avignon” and that what has been marked as exhibit so-and-so is in fact that unfortunate painting. It is important to remember, however, that many more mundane objects may be amenable to this kind of identification. A unique contract, or one that has been signed, may be authenticated by a person who is familiar with the document or its signatures. A ring may have an inscription by which it can be identified. Even a manufactured object, like a wallet, may be identifiable by its owner after years of use have given it a unique personality.
  • The second method–identification in court of an object that has been made unique, is extremely useful since it sometimes allows a lawyer or client to avoid the pitfalls of proving a chain of custody by exercising some forethought. If a witness who can establish an object’s relevance to the case marks it with his signature, initials, or another mark that will allow him to testify that he can tell it from all other objects of its kind, that witness will be allowed to identify the object in court and thus to authenticate it. Often, if a member of the lawyer’s staff or another person early in the chain of custody marks the evidence, big problems can be avoided if a later link in the chain turns out to be missing.
  • The third and least desirable way to authenticate real evidence is by establishing a chain of custody. Establishing a chain of custody requires that the whereabouts of the evidence at all times since the evidence was involved in the events at issue be established by competent testimony.

The proponent of the evidence must also establish that the object, in relevant respects, has not changed or been altered between the events and the trial. This can sometimes be a tall order, or can require the testimony of several witnesses. If there is any time from the events in question to the day of trial during which the location of the item cannot be accounted for, the chain is broken. In that case, the evidence will be excluded unless another method of authentication can be used.


Demonstrative evidence is just what the name implies–it demonstrates or illustrates the testimony of a witness. It will be admissible when, with accuracy sufficient for the task at hand, it fairly and accurately reflects that testimony and is otherwise unobjectionable. Typical examples of demonstrative evidence are maps, diagrams of the scene of an occurrence, animations, and the like. Because its purpose is to illustrate testimony, demonstrative evidence is authenticated by the witness whose testimony is being illustrated. That witness will usually identify salient features of the exhibit and testify that it fairly and accurately reflects what he saw or heard on a particular occasion, such as the location of people or things on a diagram.

For some time in California, and in some other states, there was a controversy over whether photographs were only demonstrative in nature or whether they had evidentiary value independent of the testimony of the witness who authenticated them. This problem was particularly pressing when there was no witness who could confirm what the camera saw as, for example, where crucial identifying photographs were taken by automatic cameras.

Fortunately, the courts in California and most other states seem to have reached the only sensible solution, which is that photographs can be either real or demonstrative evidence depending on how they are authenticated. When a photograph is authenticated by a witness who observed what is depicted in it and can testify that it accurately reflects what he saw, the photograph is demonstrative evidence. When it is authenticated by a technician or other witness who testifies about the operation of the equipment used to take it, it is real evidence and is, in the language of the courts, a “silent witness.”


Documentary evidence is often a kind of real evidence, as for example where a contract is offered to prove its terms. When a document is used this way it is authenticated the same way as any other real evidence–by a witness who identifies it or, less commonly, by witnesses who establish a chain of custody for it. However, because they contain human language, and because of the historical development of the common law, documents present special problems not presented by other forms of real evidence, such as when they contain hearsay.

When dealing with documentary evidence, it is a good idea to ask yourself four questions:

  1. Is there a parol evidence problem?
  2. Is there a best evidence problem?
  3. Is there an authentication problem?
  4. Is there a hearsay problem?

The parol evidence rule, which bars the admission of extrinsic evidence to vary the terms of a written agreement, is usually considered a matter of substantive law, not of rule of evidence. Accordingly, we will not deal with it here.

As has been noted above, documents can be authenticated the same way as any other real evidence.

Evid. Code § 1400, 1401, 1410-1416. Material alterations must be accounted for.

Evid. Code § 1402. There are also specifically approved methods of authenticating documents listed in the Evidence Code, including the submission to the finder of fact of a known exemplar of a signature for comparison with the signature on a disputed document,

Evid. Code § 1417, authentication by evidence of a reply,

Evid. Code § 1420, and authentication by content, Evid. Code § 1421.

In addition, some documents, such as certified copies of public records, official documents, newspapers, periodicals, trade inscriptions, acknowledged documents to prove the acknowledgment, certificates of the custodians of business records, and certain commercial paper and related documents are, to one extent or another, self authenticating under either California law or the federal rules. Evid. Code § 1450 et seq., 1530 et seq., 1562; Fed. Rules Evid. 901, 902.

We will cover the hearsay rule as a separate topic.

The best evidence rule provides that, where a writing is offered in evidence, a copy or other secondary evidence of its content will not be received in place of the original document unless an adequate explanation is offered for the absence of the original.

Evid. Code § 1500 et seq.; Fed. Rules

Evid. 1002. In California, testimonial and other secondary evidence of the document’s content is also generally forbidden.

Evid. Code §§ 1500, 1508.

The best evidence rule arose during the days when a copy was usually made by a clerk or, worse, a party to the lawsuit. Courts generally assumed that, if the original was not produced, there was a good chance of either a scrivener’s error or fraud. Now that “copy” usually means “photocopy,” the chance of a copy being in error, as opposed to simply illegible, is slight. In addition, courts are reluctant to require needless effort and delay where there is no dispute about the fairness and adequacy of a photocopy.

Accordingly, both California law and the federal rules allow the use of mechanically produced duplicates unless a party has raised a genuine question about the accuracy of the copy or can show that its use would be unfair. Evid. Code §§ 1500 et seq.; Fed. Rules Evid. 1003. However, there is always a danger of a party questioning a document, so it is important to remember that, unless you have a stipulation to the contrary, or your document fits one of the exceptions listed in the statute, you must be ready to produce originals of any documents involved in your case or to produce evidence of why you can’t.

Under both California law and the federal rules, compilations or summaries of voluminous records may be received where the originals are available for examination by the other parties. Evid. Code § 1509.


Testimonial evidence is the most basic form of evidence and the only kind that does not usually require another form of evidence as a prerequisite for its admissibility. See Evid. Code § 702(b); Fed R. Evid. 602. It consists of what is said in the court at the proceeding in question by a competent witness.

In general, a witness is competent if he meets four requirements:

  1. He must, with understanding, take the oath or a substitute. Evid. Code §§ 710, 701; Fed. Rules Evid. 603.
  2. He must have personal knowledge about the subject of his testimony. In other words, the witness must have perceived something with his senses that is relevant to the case. Evid. Code § 702; Fed. Rules Evid. 602.
  3. He must remember what he perceived.
  4. He must be able to communicate what he perceived. Evid. Code § 701(a)(1).

There are other rules of competence that relate to special circumstances, such as the rule that a juror is generally incompetent to impeach his own verdict or that, at least in federal court, a judge is not competent to testify in a trial over which he is presiding, but these and other rules like them rarely come up in practice. Evid. Code §§ 1150, 703; Fed. Rules Evid. 606, 605.

In addition, in keeping with the modern trend to view issues that were previously thought to involve questions of competence, which could result in the exclusion of evidence, as presenting instead questions of weight for the finder of fact to evaluate, the rules of competence are very liberally construed and will rarely result in the exclusion of evidence. For example, the requirement that a witness take the oath or a substitute permits virtually any kind of affirmation by which the witness, in effect, promises to tell the truth. Evid. Code § 165. The “understanding” of the oath or affirmation that is required can be that of a small child or mentally disabled person. Evid. Code § 701, 710; People v. McIntyre (1967) 256 Cal.App.2d 894, 898; 64 Cal. Rptr. 530, 533. The communication that is required may be in writing or through an interpreter, whether of spoken or of sign language. Evid. Code § 701, 752, 754; Fed. Rules Evid. 604. In addition, deficiencies in knowledge generally affect only weight, so long as the witness perceived something relevant.

Even if a witness forgets what he is supposed to be testifying about, the law allows you to supplement his memory.

  1. First, you can ask for a recess so that the witness can walk around and calm his nerves.
  2. Second, you can ask a leading question to try to refresh his recollection. This is an exception to the usual rule against the use of leading questions during direct examination.
  3. Third, you can attempt to refresh the witness’s recollection in another way.

This method is commonly called “past recollection refreshed.” Before you can try to refresh the witness’s memory he must say that he can’t remember the fact you are trying to elicit. Then he must say that the refreshing object might help him remember. Anything that the witness says might help him may be used–his own notes, notes or documents prepared by others, a videotape of events, the smell of a decedent’s perfume, a snow-cone, or a recording of the Beach Boys singing “Surf City USA.” If the memory refresher is a writing, it must be provided to opposing counsel. This is true whether the witness looks at it on the stand or before he testifies, as for example, during preparation by counsel. In California, the unexcused failure to produce writings that have been used by a witness to refresh his memory will result in his testimony being stricken!

Evid. Code § 771. The witness is permitted to look at, smell, listen to, touch, or taste the memory refresher. When he is done, you withdraw it from him and ask whether he can now remember the fact you are interested in. If, after all this, the witness remembers what you are after, he is permitted to answer. Fed. Rules Evid. 612.

The memory refreshing thing is not evidence and cannot be received as such, though it must be made available to the opposing party and may be used by him for cross examination or for any other proper purpose, including the introduction of portions of it that relate to the witness’s testimony. Fed. Rules Evid. 612. With present recollection refreshed, it is the answer of the witness, after his memory has been refreshed, that is evidence. Of course, your adversary may comment on the frailty of your witness’s memory when he argues about the weight to be attached to the testimony.

Even if your efforts to fan the embers of memory with memory refreshers fail to produce a flame, there is still hope. If the witness has previously recorded, directed the recording of, or verified the accuracy of a writing or other portrayal of the fact you are interested in, you can use the fourth method of aiding or supplementing his memory by offering the writing as a past recollection recorded. Evid. Code § 1237. First, the witness must say that he no longer remembers the fact. Then you try to refresh the witness’s memory with the writing or other recording you intend to use. If you can refresh the witness’s memory, he will be permitted to answer the question. If the writing fails to refresh the witness’s memory, he must identify it as one that he made or saw when he did remember the fact in question and that he knew then that the writing was accurate. Evid. Code § 1237. With past recollection recorded, the witness never answers the question and the writing is the evidence.

Because it is an out of court statement that is offered to prove the truth of its content, a past recollection recorded is hearsay. However, it is admissible under its own exception to the hearsay rule. Evid. Code § 1237(a); Fed. Rules Evid. 803(5). In addition, like any other documentary evidence, a past recollection recorded must meet the requirements of the best evidence rule. Unlike other documentary evidence, while a past recollection recorded may be read into the record, it may not be shown to the jurors or taken with them when they retire to deliberate. Id.

Bias, interest, prejudice, and other grounds to doubt the credibility of a witness go only to the weight of his testimony and do not affect his competence. In particular, it is not a valid objection to say that a statement by a witness is “self-serving.” Presumably, most or all statements by party witnesses are or are intended to be self serving.


On direct examination, you are generally not permitted to ask leading questions. Fed. Rules Evid. 611(c). Direct examination is questioning by the lawyer who calls the witness to testify concerning matters that into which he is the first party to inquire. Evid. Code § 760. A leading question is one that suggests an answer or substitutes the words of the lawyer for those of the witness. These are questions like “You told the defendant that you were relying on him for advice, didn’t you?”

Questions that call for an answer of “yes” or “no” are not necessarily leading. For example, most courts would allow you to ask a question like “Did you ever tell the defendant that you wanted the goods?” However, questions that call for a yes or no answer can be leading if they form a pattern that leads the witness through his testimony or reduces the witness to adopting the descriptions of his lawyer. For example, the following is clearly leading:

Q: When you entered the room did you see the defendant there?
A: Yes.
Q: Was he visibly agitated?
A: Yes.
Q: Did you ask him whether he intended to deliver the goods you had ordered?
A: Yes.
Q: Did he tell you that he had no intention of doing so?
A: Yes.

Other cases are not so clear:

Q: When you met the defendant that night, what was his physical condition?
A: He was swaying from side to side.
Q: Did he seem to you to be drunk?
A: Yes.

As you can see, in many ways, leading is a matter of degree, and borderline cases are matters of judgment and within the court’s discretion, as is the question of when to allow such leading questions on direct. Most of the time, when an objection is sustained to a leading question, it is not difficult to rephrase the question to make it unobjectionable:

Q: When you saw the defendant that night, was he drunk?
Counsel: Objection. Leading.
Court: Sustained.
Q: What was the defendant’s physical condition when you saw him?
A: He was drunk as a skunk.

As this last exchange shows, not only is eliciting testimony with nonleading questions proper, it is also usually more effective to let the witness tell the story if he can.

Leading questions are permitted on direct in several circumstances. We have already discussed the propriety of a leading question to refresh a witness’s recollection. Leading questions are also usually permitted in dealing with matters of background, or to direct the witness’s attention to a particular time and place or to a particular aspect of a situation. For example, the following should usually be permitted:

Q: Were you at Sloppy Louie’s on the evening of the twenty fifth of January?
A: Yes.
Q: Did you see the defendant’s car parked outside?
A: Yes.
Q: Was there anyone inside the car?
A: Yes.
Q: Who?
A: The defendant, that dirty rotten skunk.
Counsel: I move to strike everything after “the defendant” as unresponsive, irrelevant, incompetent, immaterial, and prejudicial.
Court: So stricken.

In the example above, while part of the witness’s answer was objectionable for other reasons, the questioning would probably not be considered improper, although the first three questions might be considered leading.

Leading questions may be allowed where, in the judge’s sound discretion, they will help to elicit the testimony of a witness who, due to tender age, incapacity, or limited intelligence, is having trouble communicating his evidence. Fed. Rules Evid. 611(c). They are also allowed when examining an adverse or hostile witness. Evid. Code § 776; Fed. Rules Evid. 611(c). Witnesses are adverse or hostile when their interests or sympathies are likely to lead them to resist testifying forthrightly or who fall into certain defined categories. Generally, an adverse party or a witness identified with an adverse party is considered hostile for the purposes of this rule. Evid. Code § 776; Fed. Rules Evid. 611(c).

The converse of a leading question is one that calls for a narrative answer. Questions that require a witness to tell a story without responding to specific questions deprive your opponent of the opportunity to interpose an objection before the witness says something that is inadmissible. They often also elicit rambles that waste the time of the court and the parties. The following is an example:

Q: What happened next?
A: Then Smittie told me about how he had seen the defendant attack the plaintiff from behind with a baseball bat.
Counsel: I move to strike that entire answer as hearsay.
Court: So stricken. The jury is instructed to disregard the last answer.


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This post was created by support on December 28, 2020.