The adversarial system or adversary system or accusatorial system or accusatory system is a legal system used in the common law countries where two advocates represent their parties' case or position before an impartial person or group of people, usually a judge or jury, who attempt to determine the truth and pass judgment accordingly. It is in contrast to the inquisitorial system used in some civil law systems where a judge investigates the case.
In a legal dispute, one party has the burden of proof to show that they are correct, while the other party has no such burden and is presumed to be correct. The burden of proof requires a party to produce evidence to establish the truth of facts needed to satisfy all the required legal elements of the dispute.
In statistical hypothesis testing, the alternative hypothesis is one of the proposed proposition in the hypothesis test. In general the goal of hypothesis test is to demonstrate that in the given condition, there is sufficient evidence supporting the credibility of alternative hypothesis instead of the exclusive proposition in the test. It is usually consistent with the research hypothesis because it is constructed from literature review, previous studies, etc. However, the research hypothesis is sometimes consistent with the null hypothesis.
The base rate fallacy, also called base rate neglect or base rate bias, is a type of fallacy in which people tend to ignore the base rate in favor of the individuating information. Base rate neglect is a specific form of the more general extension neglect.
Batson v. Kentucky, 476 U.S. 79 (1986), was a landmark decision of the United States Supreme Court ruling that a prosecutor's use of a peremptory challenge in a criminal case—the dismissal of jurors without stating a valid cause for doing so—may not be used to exclude jurors based solely on their race. The Court ruled that this practice violated the Equal Protection Clause of the Fourteenth Amendment. The case gave rise to the term Batson challenge, an objection to a peremptory challenge based on the standard established by the Supreme Court's decision in this case. Subsequent jurisprudence has resulted in the extension of Batson to civil cases and cases where jurors are excluded on the basis of sex.
Beyond (a) reasonable doubt is a legal standard of proof required to validate a criminal conviction in most adversarial legal systems. It is a higher standard of proof than the standard of balance of probabilities commonly used in civil cases because the stakes are much higher in a criminal case: a person found guilty can be deprived of liberty or, in extreme cases, life, as well as suffering the collateral consequences and social stigma attached to a conviction. The prosecution is tasked with providing evidence that establishes guilt beyond a reasonable doubt in order to get a conviction; albeit prosecution may fail to complete such task, the trier-of-fact's acceptance that guilt has been proven beyond a reasonable doubt will in theory lead to conviction of the defendant. A failure for the trier-of-fact to accept that the standard of proof of guilt beyond a reasonable doubt has been met thus entitles the accused to an acquittal. This standard of proof is widely accepted in many criminal justice systems, and its origin can be traced to Blackstone's ratio, "It is better that ten guilty persons escape than that one innocent suffer."
In American and Australian law, the right of peremptory challenge is a right in jury selection for the attorneys to reject a certain number of potential jurors without stating a reason. Other potential jurors may be challenged for cause, i.e. by giving a good reason why they might be unable to reach a fair verdict, but the challenge will be considered by the presiding judge and may be denied. A peremptory challenge can be a major part of voir dire. A peremptory challenge also allows attorneys to veto a potential juror on a "hunch".
In United States law, ineffective assistance of counsel (IAC) is a claim raised by a convicted criminal defendant asserting that the defendant's legal counsel performed so ineffectively that it deprived the defendant of the constitutional right guaranteed by the Assistance of Counsel Clause of the Sixth Amendment to the United States Constitution. Ineffectiveness claims may only be brought where the defendant had the right to counsel, ordinarily during the critical stages of a prosecution.
Rice v. Collins, 546 U.S. 333 (2006), was a decision by the Supreme Court of the United States regarding a prosecutor's use of a peremptory challenge to remove a young African American woman, Juror 16, from a defendant's drug trial jury in a California court case, based on her youth and on her alleged "eye rolling" in answer to a question. The defendant, Steven Martell Collins, challenged the striking of Juror 16, saying her exclusion was based on race, but the trial judge agreed that the prosecutor's reasons were race-neutral. The California Court of Appeal upheld the trial court's ruling, and the Federal District Court dismissed Collins' habeas corpus petition with prejudice. However, the Ninth Circuit Court of Appeals reversed and remanded, stating that the dismissal was unreasonable based, among other reasons, on the lack of evidence that the eye rolling had occurred.
Ashe v. Swenson, 397 U.S. 436 (1970), was a decision by the United States Supreme Court, which held that "when an issue of ultimate fact has once been determined by a valid and final judgment, that issue cannot again be litigated between the same parties in any future lawsuit." The Double Jeopardy Clause prevents a state from relitigating a question already decided in favor of a defendant at a previous trial. Here, the guarantee against double jeopardy enforceable through the Fifth Amendment provided that where the defendant was acquitted of robbing one victim, the government could not prosecute the criminal defendant in a second trial for a different victim in the same robbery.
Statistical proof is the rational demonstration of degree of certainty for a proposition, hypothesis or theory that is used to convince others subsequent to a statistical test of the supporting evidence and the types of inferences that can be drawn from the test scores. Statistical methods are used to increase the understanding of the facts and the proof demonstrates the validity and logic of inference with explicit reference to a hypothesis, the experimental data, the facts, the test, and the odds. Proof has two essential aims: the first is to convince and the second is to explain the proposition through peer and public review.
Escola v. Coca-Cola Bottling Co., 24 Cal.2d 453, 150 P.2d 436 (1944), was a decision of the Supreme Court of California involving an injury caused by an exploding bottle of Coca-Cola. It was an important case in the development of the common law of product liability in the United States, not so much for the actual majority opinion, but for the concurring opinion of California Supreme Court justice Roger Traynor.
Griffin v. California, 380 U.S. 609 (1965), was a United States Supreme Court case in which the Court ruled, by a 6–2 vote, that it is a violation of a defendant's Fifth Amendment rights for the prosecutor to comment to the jury on the defendant's declining to testify, or for the judge to instruct the jury that such silence is evidence of guilt.
People v. Berry is a voluntary manslaughter case that is widely taught in American law schools for the appellate court's unusual interpretation of heat of passion doctrine. Although the defendant had time to "cool down" between his wife's verbal admission of infidelity and the killing, the California Supreme Court held that the provocation in this case was adequate to reduce a murder charge to manslaughter. The lower court had relied on the traditional definition of "adequate provocation" in its jury instructions. The California Supreme Court reversed Berry's murder conviction, while affirming Berry's conviction for assault using deadly force.
Plea bargaining in the United States is very common; the vast majority of criminal cases in the United States are settled by plea bargain rather than by a jury trial. They have also been increasing in frequency—they rose from 84% of federal cases in 1984 to 94% by 2001. Plea bargains are subject to the approval of the court, and different States and jurisdictions have different rules. Game theory has been used to analyze the plea bargaining decision.
The United States Constitution contains several provisions regarding the law of criminal procedure.
Jurimetrics is the application of quantitative methods, and often especially probability and statistics, to law. In the United States, the journal Jurimetrics is published by the American Bar Association and Arizona State University. The Journal of Empirical Legal Studies is another publication that emphasizes the statistical analysis of law.
Misuse of p-values is common in scientific research and scientific education. p-values are often used or interpreted incorrectly; the American Statistical Association states that p-values can indicate how incompatible the data are with a specified statistical model. From a Neyman–Pearson hypothesis testing approach to statistical inferences, the data obtained by comparing the p-value to a significance level will yield one of two results: either the null hypothesis is rejected, or the null hypothesis cannot be rejected at that significance level. From a Fisherian statistical testing approach to statistical inferences, a low p-value means either that the null hypothesis is true and a highly improbable event has occurred or that the null hypothesis is false.
Chapman v. California, 386 U.S. 18 (1967), was a decision by the Supreme Court of the United States that a federal "harmless error" rule must apply, instead of equivalent state rules, for reviewing trials where federally-protected rights had been violated.
Math on Trial: How Numbers Get Used and Abused in the Courtroom is a book on mathematical and statistical reasoning in legal argumentation, for a popular audience. It was written by American mathematician Leila Schneps and her daughter, French mathematics educator Coralie Colmez, and published in 2013 by Basic Books.
