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Evidence
Wayne State University Law School
Moran, David A.

Chapter 3. Relevance


FRE 402:
Irrelevant Evidenceis Inadmissible.
Relevant Evidence is Admissible unless something else bars it:
Constitution (ex. no self-incrimination)
Statute (ex. wiretapping laws, banking privacy laws)
Other Rules of Evidence
Other Rules (ex. Fed Rules of Civil Pro – discovery rules)

FRE 401: Relevant Evidence– increases or decreases the probability of a material proposition. (i.e. To be relevant, evidence must either raise or lower the probability that would be assigned to the proposition in the absence of the evidence)
Material Proposition – something that is at issue in the litigation.
What propositions are material?
Elements of a claim or defense.
Or subsidiary propositions that are so closely related to an elemental proposition that the subsidiary proposition may itself be considered a material proposition.
Relevant evidence must cite a material proposition to which it is relevant.

Relevant evidence need only alter the probability of a material proposition. It is not necessary that the evidence be conclusive of the case. A brick ¹ a wall.
Additionally, for an item of evidence to be admissible it doesn’t have to be sufficient in itself to prove the party’s contention.
It’s up to the proponent of the evidence to explain why the evidence is relevant.
Relevance of evidence doesn’t guarantee it will be admissible, because countervailing factors may weigh in favor of exclusion…

FRE 403: Exclusion of Relevant Evidence on Grounds of Prejudice, Confusion, or Waste of Time
Relevant Evidence Excluded if probative value is substantially outweighed by:
1. Misleading Jury
2. Confusion of the Issues
3. Danger of Unfair Prejudice – bias or overvaluation of the evidence
4. Waste of Time
5. Considerations of Undue Delay
6. Needless Presentation of Cumulative Evidence

Probative Value = how much does it change the probability?
Rule favors admissibility if there is a tie between probative value and one of the above.
Rule 403 doesn’t state all of the considerations that might weigh against the admissibility of probative evidence – such as intrusions on the personal life of witness and hopes of inducing the proponent to produce better evidence.

Standard of Review for Evidentiary Rulings: Abuse of Discretion. Very deferential.
Judges make tons of these rulings in a single trial. Any one decision is unlikely to change the outcome of the trial. The judge doesn’t have a lot of time to make these decisions. If they were often overruled, you would never be able to get trials done b/c you’d always be sending them back.  
MI Sup Ct example – Banks.  Δ’s fingerprints found in victim’s house. Said he just broke in and stole drugs but didn’t kill her. Judge allowed suppression of evidence that victim had cocaine in her blood stream, which made Δ look like a liar. Appeals overruled.

Gruesome crime scene photos. Are they relevant?  
Helps increase the proposition that the victim is dead. But, maybe argue Unfair Prejudice (jury will be disturbed; they’ll really want to punish someone, which will prejudice the Δ).
This argument almost never works. The photos show more than just that a person was killed; they show how the person was killed. Random act of violence v. personal hatred (ex. stabbed a bunch of times).
This could help connect the Δ to the crime too. Someone who has extreme hatred for victim must know them somehow.

In order to know if evidence has probative value you need to know the prior probability. Bayes Theorem.
Prosecutor’s Fallacy is not taking into account the prior probability.

Example 1:
In Barefoot v. Estelle, the Ct allowed in psychiatric evidence regarding the future dangerousness of the Δ. Blackmun dissented saying that studies indicate that psychiatrists are accurate only 1/3 of the time.
Suppose there is an oil device that gives you a 1/3 chance of finding oil (1/10 is the baseline rate). When you have the device it’s more probable that you’ll find oil than if you don’t have the device.
Analogy doesn’t work as well for psychologist case – don’t have a baseline probability.  
If 1/10 of murders are likely to commit a future murder, and doctors are accurate 1/3 of the time, it becomes the same as the oil example.
What if baseline is ½? Then it’s bad testimony; you get it right ½ of the time, docs are only right 1/3.
What if 1/3 is the baseline? Doctor’s testimony isn’t relevant b/c it doesn’t change the probabilities.
Suppose ¼ is the baseline, and doctors get it right 1/3. It will be relevant b/c it increases the probability.
But, could argue the increase isn’t much compared to unfair prejudice. Jury is going to defer to the doctor and going to be blind to other evidence that suggests Δ isn’t dangerous.

Example 2:
Machine for detecting explosives at airport. 99.9% accurate.
1000 bags w/explosives. It’s going to ring 999 times.
1000 bags w/o explosives. It’ll ring once.
At metro airport, the machine rings. 1 million bags per year. What is the probability it has explosives?
We don’t know the prior probability that a bag at metro contains explosives.
How many of those million bags contain explosives? Let’s say 1/year.
There is a 99.9% chance that bag will ring.
But… we’ve got 999,999 w/o explosives. About 1000 of those will ring.
So, the chance that the bag that rings actually has explosives is about 1 in 1000.
Prosecutor’s Fallacy is not taking into account prior probability.
But, is it relevant that the machine rang to the proposition that the bag contained a bomb? Yes, the probability before you ran the machine was 1 in a million. After you ran it through the machine the odds are 1000 to 1.
Chapter 4. Competence



FRE 601: General Rule of Competency
Every person is competent to be a witness except as provided in the rules.
When state law provides the substantive rule of decision, it also governs competence questions. (Most states do have restrictions on who is competent to testify.

This was not the rule under common law, where lots of people couldn’t testify b/c their credibility was deemed suspect. Ex. atheists, some children, people with felony records, criminal Δs in many jurisdictions.
Thought criminal Δs had an incentive to lie; penalty for perjury is much less than some criminal penalties.
Now, the common law disqualifications have been nearly eliminated, and instead the grounds of suspicion may be presented and argued to the jury.

Rationale for Rule 601:
Incompetence rules sacrificed valuable info and undermined quest for truth. Also, nobody’s perfect. Credibility of many witnesses may be suspect even if they don’t fit into one of the excluded groups.
Fed rules take the view that the jury figure out for themselves who to believe and who not to believe.
Advisory Committee: The Q is one particularly suited to the jury as one of weight and credibility.
Testimonial Incapacities:
·         Bad Memory – might not remember accurately.
·         Bad Sincerity (Lying!)
·         Bad Perception – Deals with witness’ 5 senses. Witness may have heard/saw/smelt it wrong.
·         Bad Articulation
o   If any of these are off, we’re likely to get inaccurate testimony.
o   Cross-examination can be used to demonstrate one of these has gone wrong.

FRE 610: Religious Beliefs or Opinions
Evidence of the beliefs or opinions of a witness on matters of religion is not admissible for the purpose of showing that by reason of their nature the witness’ credibility is impaired or enhanced. Per se exclusion.

Although this info would be relevant to know, we keep it out. Why? Jurors may put diff weight on testimony just based on their religion. Separation of church and state. Prevent discrimination against religious minorities.
EX: Sexual lawsuit against Archdiocese. Cannot ask if they are a Catholic b/c it is barred by 610. However, can ask if they’re a member of the Archdioceses b/c it shows the witnesses is biased. Similar to, in a lawsuit against WSU, asking if witness is a WSU alum. Helps with showing the person’s sincerity—the person is biased. 

Rule 603: Oath or Affirmation
Before testifying, witness has to declare that they will testify truthfully, by oath or affirmation administered in a form calculated to awaken the witness’ conscience and impress the witness’ mind w/the duty to do so.

Rule tries to encourage truth telling. It makes it more likely that the witness will take extra care with the truth, if for no other reason than that lying under oath is a crime.

This rule gives you a way to argue that a witness shouldn’t be able to testify. If they don’t understand the oath, they can’t testify. It doesn’t “awaken their conscious.” They’re incapable of understanding it. This argument very seldom succeeds b/c 601 seems to be so inclusive.

This issue most often arises in the case of child witnesses…
Common law approach to child witnesses: children of insufficient maturity were consider

as is “woman,” “blonde,” “red,” and “dress.”
Lay Opinion must be on a subject with which witness is familiar but with which jury is not. Witness’s function is to put the jury in as good a position as the witness herself to evaluate the data necessary for fact finding.
It’s impossible to eliminate the evaluative aspects of witness testimony:
People naturally assess and organize data in their own minds before reporting them.
“I saw George” vs. “I saw a male figure, about 50, 6 ft tall, etc.”
Limited capacity of the jury to understand information presented in weird ways
“Red” vs. talking about wavelengths.
Chapter 5. Expert Evidence
Second Circuit: Question ought always to be whether it is more convenient to insist that the witness disentangle in his own mind those constituent factors on which his opinion is based; or let him state his opinion and leave to cross-exam a searching inquisition to uncover its foundations.

FRE 702: Testimony by Experts
If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue,
A witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise if:
Daubert Standard:
(1) The testimony is based upon sufficient facts or data AND
(2) The testimony is the product of reliable principles and methods, AND
(3) The witness has applied the principles and methods reliably to the facts of the case.

Expert witnesses do not need personal knowledge and can express opinions w/in expertise.
Expert must be telling the jury something it might not know or can’t figure out on its own.
The less well known or more counterintuitive expert evidence is, the more likely it is to be let in.
Ex. Don’t need an expert to tell you that you’ll die if you fall out of an 8th story window, but you’ll need them to tell you how fast you’ll fall.
Ex 2. Probably couldn’t put an expert on the stand to talk about credibility of another witness’ testimony. This is something the jury can do on their own.
Ex 3. Many cts let experts testify about the dangers/problems with eyewitness testimony.
Note: you don’t have to have advanced degrees to be an “expert.” Rule 702 doesn’t impose technical limits on the source of an expert’s “specialized knowledge.”
Note 2: Rule does not prevent a party to the action from being an “expert witness.” However, this may not be the most advisable plan b/c the other party get to cross-examine, and the jury might not believe your opinions b/c you’re “biased.” If also looks bad if the only “expert” who agrees with you is you.
One check on the use of expert testimony is money!

Witness must be qualified or certified as an expert on the subject in issue.
This is a matter for the Ct to determine under FRE 104(a).
Common type of statute provides that if Δ is a specialist then any expert testifying on the standard of care must have been a specialist, actively engaged in practice or education, in the same field at the time of the occurrence that is the basis for the action. If Δ is a board-certified specialist then the expert must be board-certified as well.

In some cases, expert testimony is required.
Professional Malpractice Claims.
Expert testimony is required to support the claim that the Δ’s conduct fell short of professional standards. (Maybe not needed if deficiency was super obvious)
Future Pain and Suffering Damages
Ct may require expert testimony to show injury is likely to have a long-term impact.