Logic and Reasoning and Human Factors in Decision Making and Testimony Preparation

deductive logic?

Starts with a general rule and applies it to a specific case.

example of deductive logic?

General rule: fingerprints are unique. Specific case: latent print matches a known print. Conclusion: they came from the same person.

Easy way to remember deductive logic?

General → Specific

Strengths of deductive logic?

Strong certainty if the premises are true, follows a logical structure, and produces valid conclusions.

Weaknesses of deductive logic?

Depends on accurate premises and may oversimplify real-world situations.

What is inductive logic?

Uses observations and experience to make a likely conclusion.

example of inductive logic?

An examiner compares thousands of prints and concludes the current prints are likely from the same person based on previous experience.

inductive logic

Experience → Probability

Strengths of inductive logic?

Uses observations, identifies patterns, and is practical and flexible.

Weaknesses of inductive logic?

Conclusions are probable—not certain—and may be influenced by limited or biased observations.

What is abductive logic?

Chooses the most likely explanation based on the available evidence.

example of abductive logic?

A latent print has many corresponding ridge details and no significant unexplained differences, making the suspect the best explanation.

Easy way to remember abductive logic?

Evidence → Best Explanation

Strengths of abductive logic?

Useful when evidence is incomplete and supports real-world decision-making.

Weaknesses of abductive logic?

Does not guarantee certainty and different examiners may interpret evidence differently.

categorical conclusions

Identification, Exclusion, and Inconclusive.

Benefits of categorical conclusions?

Clear answers, structured ACE-V process, and useful for investigations.

Limitations of categorical conclusions?

Cannot prove absolute certainty, lack fixed standards, and may be affected by human error or bias.

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Benefits of continuous statistical conclusions?

Describe the strength of evidence, recognize uncertainty, and reduce subjectivity.

continuous statistical conclusions?

Difficult for jurors to understand, require additional training, and may not capture everything an examiner observes.

What is a likelihood ratio?

Compares how strongly the fingerprint evidence supports that the suspect is the source versus someone else.

What is posterior probability?

The probability the suspect is the source after considering the fingerprint evidence and other case information.

Why is posterior probability controversial?

It depends on initial assumptions, so many experts believe final probability should be left to the judge or jury.

What is faulty reasoning?

Drawing a conclusion that doesn't logically follow from the evidence.

circular reasoning

Proving something by simply restating the conclusion.

transposing the conditional?

Incorrectly reversing a true conditional statement.

prosecutor's fallacy?

Confusing how rare evidence is with how likely a suspect is guilty.

appeal to authority?

Accepting a claim as true solely because an expert says so.

false dichotomy?

Presenting only two choices when other possibilities exist.

What are decision-based mistakes?

Honest mistakes where an examiner makes an incorrect decision despite using their training and experience.

What are skill-based mistakes?

Errors during routine tasks caused by distractions, loss of focus, or memory lapses.

What are perception-based mistakes?

Errors caused by failing to correctly see or interpret fingerprint information.

What are the two types of perception-based mistakes?

Not all data perceived; data perceived but compared inadequately.

What are violations?

Intentional departures from established procedures or protocols.

Two types of violations?

Willful noncompliance and exceptional violations.

adverse mental states?

Temporary mental conditions like stress or workload that affect focus and judgment.

What are adverse physiological states?

Physical conditions like fatigue, illness, or discomfort that reduce performance.

What is the technical environment?

The tools, software, and equipment used during fingerprint examinations.

technical environment issues?

Poor system integration, faulty equipment, poor software design, and maintenance problems.

physical environment?

Laboratory conditions that affect comfort, focus, and accuracy.

Examples of physical environment issues?

Poor lighting, cluttered workspaces, distractions, uncomfortable temperatures, and safety concerns.

What human factors contributed to the Dandridge case?

Confirmation bias, insufficient evaluation, misinterpretation of ridge detail, and false inclusion.

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What is cognitive bias?

A psychological influence that can affect an examiner's judgment, perception, and decision-making.

cognitive bias?

Expecting a fingerprint to match a suspect and unintentionally focusing on similarities while overlooking differences.

Ways to mitigate human factors?

Verification, following SOPs, detailed documentation, training, remaining objective, recognizing personal bias, taking breaks, maintaining an organized workspace, and seeking second opinions.

Defendant?

A person or organization accused or sued in court.

Discovery?

The exchange of information between both sides before trial.

Exculpatory evidence?

Evidence that helps prove the defendant may be innocent or creates reasonable doubt.

Hearsay?

Testifying about what someone else said instead of that person testifying.

in limine?

A request before trial to admit or exclude evidence.

Nolle prosequi (Nol Pros)?

The prosecutor decides to stop pursuing criminal charges.

Plea bargain?

An agreement where the defendant pleads guilty in exchange for a more favorable outcome.

Prejudicial effect?

Evidence that unfairly influences a judge or jury.

Probable cause?

Enough facts to reasonably believe a crime occurred or someone committed it.

Probative value?

The usefulness of evidence in proving a fact.

Rule 16?

Requires the government and defense to exchange certain evidence before trial.

Reliability?

The consistency and repeatability of a method or result.

Voir dire?

The process of selecting an impartial jury.

List the criminal case process in order.

Investigation → Arrest → Charging → Initial Appearance → Preliminary Hearing/Grand Jury → Arraignment → Discovery → Plea Bargain or Trial → Sentencing → Appeals → Post-Conviction Review.

Rule 401?

Relevant evidence makes a fact more or less probable.

Rule 402?

Relevant evidence is generally admissible.

Rule 403?

Relevant evidence may be excluded if unfair prejudice substantially outweighs its value.

Rule 702?

Governs expert witness testimony.

Rule 703?

Experts may base opinions on facts or data they observed or reviewed.

Rule 705?

Experts may give conclusions before explaining all supporting facts.

What is chain of custody?

Documentation showing who collected, handled, and preserved evidence.

Rule 901 (Authentication)?

Evidence must be shown to be what it claims to be before admission.

Frye v. United States (1923)?

Scientific evidence must be generally accepted by the scientific community.

Daubert v. Merrell Dow (1993)?

Judges evaluate whether expert testimony is scientifically reliable and relevant.

Kumho Tire v. Carmichael (1999)?

Daubert applies to all expert testimony, not just scientific testimony.

People v. Kelly (1976)?

Voiceprint evidence was excluded because it lacked general acceptance under Frye.

General Electric v. Joiner (1997)?

Reinforced judges' gatekeeping role under Daubert.

Frye or Daubert

Virginia – Modified Daubert; Maryland – Frye-Reed; DC – Primarily Frye.

United States v. Havvard?

Fingerprint evidence is admissible under Daubert; weaknesses affect weight, not admissibility.

United States v. Llera Plaza?

Fingerprint experts may testify to identifications, but courts recognize ACE-V contains subjective elements.

Brady v. Maryland?

Requires disclosure of exculpatory evidence.

Giglio v. United States?

Requires disclosure of impeachment evidence affecting witness credibility.

United States v. Henthorn?

Prosecutors must review personnel files of government witnesses for material affecting credibility.

1st

Crime Reported and investigation starts

2nd

Arrest and Summons

3rd

Charging Decision (whether to file criminal charges)/plea negotiations

4th

Initial appearance and bail hearing

5th

Preliminary hearing or grand jury hearing

6th

Arraignment (Formally informed of charges, defendant enters a plea…Guilty…non guilty…no contest)

7th

pretrial proceeding and discovery

8th

Plea Bargaining

Trail

9th

10th

Sentencing

11th

Appeals

Post-Conviction Review

12th