Brady v. Maryland: Withheld Evidence and Due Process

Brady v. Maryland, 373 U.S. 83 (1963)

Supreme Court of the United States · Due process / disclosure

The rule

The prosecution’s suppression of evidence favorable to the accused violates due process when the evidence is material to guilt or punishment. The prosecution’s good or bad faith does not control the constitutional question.

Why it matters

Evidence that supports the defense can matter at sentencing as well as at trial. A useful research record identifies what was withheld, when it became available, how it favored the defense, and why it could affect the outcome. Not every missing document establishes a constitutional violation.

Questions to discuss with counsel

What favorable evidence was withheld? Did the prosecution team possess it? How does it change the picture presented to the factfinder? Later cases refine materiality and procedural requirements.

Read the opinion

https://www.law.cornell.edu/supremecourt/text/373/83

Educational information, not legal advice. Check later decisions, jurisdiction-specific rules, procedural requirements, and deadlines with qualified counsel.

Strickland v. Washington: Understanding Ineffective Assistance

Strickland v. Washington, 466 U.S. 668 (1984)

Supreme Court of the United States · Sixth Amendment / counsel

The two-part test

A defendant ordinarily must show both deficient performance and prejudice. Performance is assessed against an objective standard of reasonableness, with strong deference to counsel’s professional judgment. Prejudice generally requires a reasonable probability that, without counsel’s errors, the outcome would have differed—a probability sufficient to undermine confidence in the result.

Why it matters

Losing a case does not itself prove ineffective assistance. Identify the specific act or omission, the record supporting it, and its effect on the proceeding. Courts consider the circumstances facing counsel at the time rather than judging solely with hindsight.

Research checklist

Locate transcripts, counsel’s investigation records where available, omitted evidence, and the applicable procedural vehicle. Explain both parts of the test separately. Special rules may apply to particular claims, and federal habeas review can add substantial limits.

Read the opinion

https://www.law.cornell.edu/supremecourt/text/466/668

Educational information, not legal advice. Verify current authority and filing requirements with qualified counsel.

Franks v. Delaware: Challenging False Warrant Statements

Franks v. Delaware, 438 U.S. 154 (1978)

Supreme Court of the United States · Fourth Amendment / warrant affidavits

The hearing threshold

A defendant must make a substantial preliminary showing that the affiant knowingly, intentionally, or recklessly included a false statement in a warrant affidavit, and that the statement was necessary to probable cause. The challenge requires supporting evidence, not merely a disagreement with the affidavit. Negligence or innocent mistake is insufficient.

What happens at the hearing

If intentional or reckless falsity is established by a preponderance of the evidence, and the affidavit without the false material does not establish probable cause, the warrant must be voided and the resulting evidence excluded.

Research checklist

Identify the exact statement, evidence contradicting it, evidence of the affiant’s state of mind, and the remaining probable-cause facts. Claims involving omitted facts require jurisdiction-specific research into later decisions; Franks does not automatically invalidate every incomplete affidavit.

Read the opinion

https://www.law.cornell.edu/supremecourt/text/438/154

Educational information, not legal advice. Discuss the record, local rules, and deadlines with qualified counsel.

Giglio and Kyles: Witness Deals and the Full Disclosure Picture

Giglio v. United States, 405 U.S. 150 (1972)

Kyles v. Whitley, 514 U.S. 419 (1995)

Supreme Court of the United States · Witness credibility / disclosure

Giglio: promises to a key witness

An undisclosed promise of nonprosecution to a key witness can undermine the fairness of a trial. Evidence affecting credibility matters when the witness’s reliability may determine guilt or innocence. Giglio also treats the prosecutor’s office as an entity: one prosecutor’s promise cannot be disregarded simply because the trial prosecutor did not know about it.

Kyles: consider the evidence together

Materiality is assessed through the cumulative effect of suppressed favorable evidence, not by isolating each item. The prosecutor must learn of favorable evidence known to others acting for the government in the case, including police. The question is whether disclosure creates a reasonable probability of a different result—not whether acquittal was more likely than not.

Research questions

Were promises, inconsistent statements, or other credibility materials withheld? How do all suppressed items affect the case together?

Read the opinions

https://www.law.cornell.edu/supremecourt/text/405/150

https://www.law.cornell.edu/supremecourt/text/514/419

Educational information, not legal advice. Verify current law and procedural requirements with qualified counsel.