The burden of proof (Latin: onus probandi) is the obligation to shift the accepted conclusion away from an oppositional opinion to one's own position. The burden of proof may only be fulfilled by legal evidence.
The burden of proof is often associated with the Latin maxim semper necessitas probandi incumbit ei qui agit, the best translation of which seems to be: "the necessity of proof always lies with the person who lays charges."[1] This is a statement of a version of the presumption of innocence that underpins the assessment of evidence in some legal systems, and is not a general statement of when one takes on the burden of proof. The burden of proof tends to lie with anyone who is arguing against received wisdom, but does not always, as sometimes the consequences of accepting a statement or the ease of gathering evidence in its defense might alter the burden of proof its proponents shoulder. The burden may also be assigned institutionally.
He who does not carry the burden of proof carries the benefit of assumption, meaning he needs no evidence to support his claim. Fulfilling the burden of proof effectively captures the benefit of assumption, passing the burden of proof off to another party.
The burden of proof is an especially important issue in law and science.
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There are generally two broad types of burdens:
The "standard of proof" is the level of proof required in a legal action to discharge the burden of proof, that is to convince the court that a given proposition is true. The degree of proof required depends on the circumstances of the proposition. Typically, most countries have two levels of proof or the balance of probabilities:
A more detailed discussion of each standard follows below.
Reasonable suspicion is a low standard of proof in the U.S. to determine whether a brief investigative stop or search by a police officer or any government agent is warranted. It is important to note that this stop and/or search must be brief; its thoroughness is proportional to, and limited by, the low standard of evidence. A more definite standard of proof (often probable cause) would be required to warrant a more thorough stop/search. In Terry v. Ohio, 392 U.S. 1 (1968), the United States Supreme Court ruled that reasonable suspicion requires specific, articulable, and individualized suspicion that crime is afoot. A mere guess or "hunch" is not enough to constitute reasonable suspicion.
A investigatory stop is a seizure under the Fourth Amendment. The state must justify the seizure by showing that the officer conducting the stop had a reasonable articulable suspicion that criminal activity was afoot. The important point is that officers cannot deprive a citizen of liberty unless the officer can point to specific facts and circumstances and inferences therefrom that would amount to a reasonable suspicion. The officer must be prepared to establish that criminal activity was a logical explanation for what he perceived. The requirement serves to prevent officers from stopping individuals based merely on hunches or unfounded suspicions. The purpose of the stop and detention is to investigate to the extent necessary to confirm or dispel the original suspicion. If the initial confrontation with the person stopped dispels suspicion of criminal activity the officer must end the detention and allow the person to go about her business. If the investigation confirms the officer's initial suspicion or reveals evidence that would justify continued detention the officer may require the person detained to remain at the scene until further investigation is complete. In some cases, the investigation may develop sufficient evidence to constitute probable cause.
Probable cause is a relatively low standard of evidence, which is used in the United States to determine whether a search, or an arrest, is warranted. It is also used by grand juries to determine whether to issue an indictment. In the civil context, this standard is often used where plaintiffs are seeking a prejudgment remedy.
In the criminal context, the U.S. Supreme Court in United States v. Sokolow, 490 U.S. 1 (1989), determined that probable cause requires "a fair probability that contraband or evidence of a crime will be found" in determining whether Drug Enforcement Administration agents had a reason to execute a search. Courts vary when determining what constitutes a "fair probability," some say 30%, others 40%, others 51%.
A good illustration of this evidence/intrusiveness continuum might be a typical police/citizen interaction. Consider the following three interactions:
no level of suspicion required: a consensual encounter between officer and citizen
reasonable suspicion required: a stop initiated by the officer that would cause a reasonable person to feel not free to leave
probable cause required: arrest.
The "air of reality" is a standard of proof used to determine whether a criminal defense may be used. The test asks whether a defense can be successful if it is assumed that all the claimed facts are to be true. In most cases, the burden of proof rests solely on the prosecution, negating the need for a defense of this kind. However, when exceptions arise and the burden of proof has been shifted to the defendant, he is required to establish a defense that bears an "air of reality." Two instances in which such a case might arise are, first, when a prima facie case has been made against the defendant or, second, when the defense mounts an affirmative defense, such as the insanity defense.
Preponderance of the evidence, also known as balance of probabilities is the standard required in most civil cases. The standard is met if the proposition is more likely to be true than not true. Effectively, the standard is satisfied if there is greater than 50 percent chance that the proposition is true. Lord Denning, in Miller v. Minister of Pensions,[3] described it simply as "more probable than not." Until 1970, this was also the standard used in juvenile court in the United States.
Clear and convincing evidence is the higher level of burden of persuasion sometimes employed in both civil and criminal procedure in the United States. For example, a prisoner seeking habeas corpus relief from capital punishment must prove his factual innocence by clear and convincing evidence.[4]
To prove something by "clear and convincing evidence", the party with the burden of proof must convince the trier of fact that it is substantially more likely than not that the thing is in fact true. This is a lesser requirement than "proof beyond a reasonable doubt", which requires that the trier of fact be close to certain of the truth of the matter asserted, but a stricter requirement than proof by "preponderance of the evidence," which merely requires that the matter asserted seem more likely true than not.
This is the standard required by the prosecution in most criminal cases within an adversarial system and is the highest level of burden of persuasion. This means that the proposition being presented by the government must be proven to the extent that there is no "reasonable doubt" in the mind of a reasonable person that the defendant is guilty. There can still be a doubt, but only to the extent that it would not affect a "reasonable person's" belief that the defendant is guilty. If the doubt that is raised does affect a "reasonable person's" belief that the defendant is guilty, the jury is not satisfied beyond a "reasonable doubt". The precise meaning of words such as "reasonable" and "doubt" are usually defined within jurisprudence of the applicable country.
The word "beyond" in the phrase "beyond a reasonable doubt" means to the exclusion of. In other words the state's responsibility is to exclude any and all reasonable doubt as to the defendant's guilt.
“What is a reasonable doubt?” Jury instructions typically say that a reasonable doubt is a doubt based on reason and common sense and typically use phrases such as “fully satisfied” or “entirely convinced” in an effort to quantify the standard of proof.[5] The modifiers "entirely" and "fully" do not mean that you have to be 100 percent certain of the defendant’s guilt. The standard of proof is not absolute certainty. A juror is "fully satisfied" or "entirely convinced" when the state had eliminated all reasonable doubt.
"The reasonable-doubt standard plays a vital role in the American scheme of criminal procedure. It is a prime instrument for reducing the risk of convictions resting on factual error. The standard provides concrete substance for the presumption of innocence — that bedrock "axiomatic and elementary" principle whose "enforcement lies at the foundation of the administration of our criminal law."[6] . Proof beyond a reasonable doubt did not become the accepted standard in criminal cases until the middle of the nineteenth century.[7] Proof beyond a reasonable doubt was not the standard by which guilt was determined when the Bill of Rights was drafted in 1789[8] (which may explain the absence of the phrase in the constitution), nor was it an element of due process.
However juries in criminal courts in England are no longer customarily directed to consider whether there is a "reasonable doubt" about a defendant's guilt. Indeed a recent conviction was appealed after the judge had said to the jury "You must be satisfied of guilt beyond all reasonable doubt." The conviction was upheld but the Appeal Court made clear their unhappiness with the judge's remark, indicating that the judge should instead have said to the jury simply that before they can return a verdict of guilty, they "must be sure that the defendant is guilty". R v Majid [2009] EWCA Crim 2563 (12 October 2009).
One of the earliest attempts to quantify reasonable doubt was a 1971 article by Rita Simon and Linda Mahan, "Quantifying Burdens of Proof—A View from the Bench, the Jury, and the Classroom." [9] In a later analysis of the question ("Distributions of Interest for Quantifying Reasonable Doubt and Their Applications," 2006[10]) , three students at Valparaiso University presented a trial to groups of students. Half of the students decided the guilt or innocence of the defendant. The other half recorded their perceived likelihood, given as a percentage, that the defendant committed the crime. They then matched the highest likelihoods of guilt with the guilty verdicts and the lowest likelihoods of guilt with the innocent verdicts. From this, the researchers gauged that the cutoff for reasonable doubt fell somewhere between the highest likelihood of guilt matched to an innocent verdict and the lowest likelihood of guilt matched to a guilty verdict. From these samples, they concluded that the standard was between 0.70 and 0.74.
The majority of law theorists believe that reasonable doubt cannot be quantified. It is more a qualitative than a quantitative concept. As Rembar notes, "Proof beyond a reasonable doubt is a quantum without a number."[11]
Beyond the shadow of a doubt is the most strict standard of proof. It requires that there be no doubt as to the issue. Widely considered an impossible standard, a situation stemming from the nature of knowledge itself, it is valuable to mention only as a comment on the fact that evidence in a court never need reach this level. This phrase, has, nonetheless, come to be associated with the law in popular culture.
In the West, criminal cases usually place the burden of proof on the prosecutor (expressed in the Latin brocard ei incumbit probatio qui dicit, non que negat, "the burden of proof rests on who asserts, not on who denies"). This principle is known as the presumption of innocence, and is summed up with "innocent until proven guilty," but is not upheld in all legal systems or jurisdictions. Where it is upheld, the accused will be found not guilty if this burden of proof is not sufficiently shown by the prosecution.
The presumption of innocence means three things:
The presumption of innocence does not mean that the jury or anyone else must pretend or assume that the defendant is in fact innocent of the charges. Nothing the jury does can alter the fact that the defendant did or did not commit the offense. There is no intermediate state.
For example, if the defendant (D) is charged with murder, the prosecutor (P) bears the burden of proof to show the jury that D did murder someone.
In other countries, criminal law reverses the burden of proof, and there is a presumption of guilt.
However, in England and Wales, the Magistrates' Courts Act 1980, s.101 stipulates that where a defendant relies on some "exception, exemption, proviso, excuse or qualification" in his defence, the legal burden of proof as to that exception falls on the defendant, though only on the balance of probabilities. For example, a person charged with being drunk in charge of a motor vehicle can raise the defence that there was no likelihood of his driving while drunk.[14] The prosecution have the legal burden of proof beyond reasonable doubt that the defendant exceeded the legal limit of alcohol and was in control of a motor vehicle. Possession of the keys is usually sufficient to prove control, even if the defendant is not in the vehicle and is perhaps in a nearby bar. That being proved, the defendant has the legal burden of proof on the balance of probabilities that he was not likely to drive.[15]
Similar rules exist in trial on indictment. Some defences impose an evidential burden on the defendant which, if met, imposes a legal burden on the prosecution. For example, if a person charged with murder pleads the right of self-defense, the defendant must satisfy the evidential burden that there are some facts suggesting self-defence. The legal burden will then fall on the prosecution to prove beyond reasonable doubt that the defendant was not acting in self-defence.[15]
In 2002, such practice in England and Wales was challenged as contrary to the European Convention on Human Rights (ECHR), art.6(2) guaranteeing right to a fair trial. The House of Lords held that such burdens were not contrary to the ECHR:[15][16]
In civil law cases, the "burden of proof" requires the plaintiff to convince the trier of fact (whether judge or jury) of the plaintiff's entitlement to the relief sought. This means that the plaintiff must prove each element of the claim, or cause of action, in order to recover.
The burden of proof must be distinguished from the "burden of going forward," which simply refers to the sequence of proof, as between the plaintiff and defendant. The two concepts are often confused.
In Keyes v. Sch. Dist. No. 1, 413 U.S. 189 (1973), the United States Supreme Court stated: “There are no hard-and-fast standards governing the allocation of the burden of proof in every situation. The issue, rather, ‘is merely a question of policy and fairness based on experience in the different situations.’” For support, the Court cited 9 John H. Wigmore, Evidence § 2486, at 275 (3d ed. 1940). In Keyes, the Supreme Court held that if “school authorities have been found to have practiced purposeful segregation in part of a school system,” the burden of persuasion shifts to the school to prove that it did not engage in such discrimination in other segregated schools in the same system.
In Director, Office of Workers’ Compensation Programs v. Greenwich Collieries, 512 U.S. 267 (1994), the Supreme Court explained that burden of proof is ambiguous because it has historically referred to two distinct burdens: the burden of persuasion, and the burden of production.
The Supreme Court discussed how courts should allocate the burden of proof (i.e., the burden of persuasion) in Schaffer ex rel. Schaffer v. Weast, 546 U.S. 49 (2005). The Supreme Court explained that if a statute is silent about the burden of persuasion, the court will “begin with the ordinary default rule that plaintiffs bear the risk of failing to prove their claims.” In support of this proposition, the Court cited 2 J. Strong, McCormick on Evidence § 337, 412 (5th ed. 1999), which states:
The burdens of pleading and proof with regard to most facts have been and should be assigned to the plaintiff who generally seeks to change the present state of affairs and who therefore naturally should be expected to bear the risk of failure of proof or persuasion.
At the same time, the Supreme Court also recognized “The ordinary default rule, of course, admits of exceptions.” “For example, the burden of persuasion as to certain elements of a plaintiff's claim may be shifted to defendants, when such elements can fairly be characterized as affirmative defenses or exemptions. See, e.g., FTC v. Morton Salt Co., 334 U.S. 37, 44-45 (1948). Under some circumstances this Court has even placed the burden of persuasion over an entire claim on the defendant. See Alaska Dept. of Environmental Conservation v. EPA, 540 U.S. 461 (2004).” Nonetheless, “[a]bsent some reason to believe that Congress intended otherwise, therefore, [the Supreme Court] will conclude that the burden of persuasion lies where it usually falls, upon the party seeking relief.”