BASIC EVIDENCE CONCEPTS
I. KINDS OF EVIDENCE
A. Direct versus circumstantial  1. Direct evidence: Direct evidence is evidence which, if believed, automatically resolves the issue. (Example: W says, “I saw D strangle V.” This is direct evidence on whether D strangled V.)
2. Circumstantial: Circumstantial evidence is evidence which, even if believed, does not resolve the issue unless additional reasoning is used. (Example: W says, “I saw D running from the place where V’s body was found, and I found a stocking in D’s pocket.” This is only circumstantial evidence of whether D strangled V.)
3. Probative value: The probative value of direct evidence is not necessarily higher than circumstantial evidence, but it will sometimes be more readily admitted by the judge.
B. Testimonial versus real and demonstrative:  1. Testimonial: Testimonial evidence arises when W makes assertions in court. The fact-finder must rely on W’s interpretation of W’s sensory data, W’s memory, etc.
2. Real and demonstrative: Real evidence is a thing involved in the underlying event (e.g., a weapon, document, or other tangible item). Demonstrative evidence is a tangible item that illustrates some material proposition (e.g., a map, chart, summary). The fact-finder may interpret either real or demonstrative evidence by use of its own senses, without intervening sensing and interpreting by a witness.
II. CONDITIONS FOR ADMITTING EVIDENCE
A. Relevant: Only relevant evidence may be admitted. (FRE 402) [10 – 16] 1. Definition: Evidence is “relevant” if it has “any tendency to make the existence of [a material] fact … more probable or less probable than it would be without the evidence.” (FRE 401)
a. “Brick is not wall”: The piece of evidence need not make a material fact more probable than not; it must merely increase the probability (even by a small amount) that the material fact is so. “A brick is not a wall,” and the piece of evidence merely has to be one brick in the wall establishing a particular fact.
2. Exclusion: Even relevant evidence may be excluded if its probative value is substantially outweighed by the danger of:
(1) unfair prejudice;
(2) confusion of the issues;
(3) misleading of the jury; or
(4) considerations of undue delay, waste of time, or needless presentation of cumulative evidence. (FRE 403)
B. Offering testimonial evidence
1. Lay (i.e., non-expert) witness:
a. W must take oath, i.e., solemnly promise to testify truthfully. (FRE 603)
b. W must testify from personal knowledge. (FRE 602)
c. W must preferably state facts rather than opinions. At common law this rule is sometimes stated as a firm requirement (although often loosely enforced). Under FRE 701, W may give an opinion if it is:
(1) rationally based on his own perceptions; and
(2) helpful to the fact-finder.
d. At common law, W must be competent, and many groups of witnesses are deemed not to be (e.g., atheists, felons, interested parties). Under Federal Rules (and by statute in most states), nearly everyone with first-hand knowledge is competent. See, e.g., FRE 601: everyone is competent (except for judges and jurors, made incompetent by Rules 605 and 606 respectively). (But the federal court must generally honor a state rule of competency in diversity cases.)
2. Experts: Same rules apply to experts as to lay witnesses, except:
a. The expert may give opinion if this will be helpful to trier (FRE 702).
b. The expert’s opinion need not be based on his personal knowledge – it may be based on information supplied by others. At common law, this is usually done by the hypothetical question. Under Federal Rules, it may be done either by the hypothetical or by out-of-court statements made to the expert (even inadmissible evidence); FRE 703. Under FRE 705, facts relied on by the expert need not be disclosed except under cross-examination or as required by court.
l suit from an auto accident, P cannot show that D has the general character trait of carelessness, or even that D is a generally careless driver, to suggest that D probably acted carelessly in the particular accident under litigation.) [20 – 22]
B. Character in issue: [22 – 23]
1. Essential element: A person’s general character, or his particular character trait, is admissible if it is an essential element of the case. (Example: P says that D has libeled him by calling him a liar. D may introduce evidence of P’s character for untruthfulness, since that character trait is an essential element of D’s defense that his statement was true.)
a. Illustrations: True “character in issue” situations are rare. Civilly, negligent entrustment (D gave dangerous instrumentality, like a car, to one he should have known was of careless or otherwise bad character) and defamation (above example) are the most common. Criminally, entrapment (prosecution rebuts by showing D was “predisposed” to commit the crime) is the only instance.
2. Types of evidence: When character is directly in issue, all three types of character evidence (specific acts, W’s opinion, or the subject’s reputation) are admissible.
C. Circumstantial evidence in civil cases: In civil cases, circumstantial evidence of character is generally inadmissible. [24 – 25] 1. Quasi-criminal acts: A few courts allow one who is charged in a civil case with conduct that would also be a crime to rebut this charge by presenting circumstantial evidence of his good character. But most courts, and the Federal Rules, do not.