A weight-of-evidence approach considers all scientific evidence relevant to a particular topic. This is in stark contrast to the “strength of evidence” assessment – a less desirable approach that considers only a subset of the evidence, such as focusing only on studies that have found a positive association between exposure to a chemical and an adverse disease or condition. For example, the regulatory classification of chemical agents as carcinogenic established by the National Toxicology Program in the past was based on strong evidence; That is, the level of positive evidence from perhaps a single study showing a statistically significant result. The weight of evidence is based on the credibility or persuasiveness of the evidence. The probative value (tendency to convince a person of the truth of a statement) of the evidence does not necessarily depend on the number of witnesses called, but on the persuasiveness of their testimony. For example, a witness may give uncorroborated but apparently honest and sincere testimony that commands faith, even if several witnesses of apparent gravity may contradict it. The question for the jury is not which side has the most witnesses, but what statements they believe. Weight of evidence refers to a systematic approach that scientists use to assess the body of scientific evidence to assess whether science supports a particular conclusion. Weight-of-evidence decisions do not involve simply counting positive and negative studies, but rely on the judgment of scientific experts to assess, review and integrate all results to reach a meaningful conclusion. Some evidence carries different weights when it comes to inducing faith about the facts and circumstances to be proved. Indeterminate, vague or improbable evidence will carry less weight than direct, unrefuted evidence. For example, a criminal accused`s statement that he never went to the crime scene would carry little weight if his fingerprints were found at the crime scene and witnesses claimed to have seen him at the scene. Similarly, the testimony of a witness who testifies on the basis of personal observation carries more weight than the testimony of a witness who testifies solely on the basis of general knowledge.

n. the strength, value and credibility of the evidence presented by one party on a question of fact in relation to the evidence presented by the other. See: Evidence, Predominance of Evidence) The gold standard for scientists, when there are conflicting results of scientific studies, is a weight-of-evidence approach that involves rigorous scientific review of all available data to make a decision. The level of credible evidence on one side of a dispute versus credible evidence on the other, particularly evidence considered by a judge or jury during a trial. In civil proceedings, the plaintiff`s burden of proof is the standard of PREDOMINANCE of evidence, which means that the plaintiff must satisfy the judge that the evidence in support of his or her case outweighs the evidence offered by the defendant in order to defend against it. In contrast, criminal proceedings require that the probative value of a defendant`s guilt be BEYOND A REASONABLE DOUBT. Hill proposed these guidelines as a tool for finding answers to fundamental questions: Is there another way to explain the facts before us? Are there other answers that are equal to or more likely than cause and effect? Hill also cautioned against waiting for full and convincing evidence of causality before taking action when circumstances warrant, saying: “All scientific work is incomplete, whether observational or experimental. Any scientific work can be disrupted or modified by the advancement of knowledge. It does not give us the freedom to ignore the knowledge we already have or postpone the action it seems to require at some point. WEIGHT OF EVIDENCE. This theorem is used to indicate that the proof of a cause is greater on one side than on the other.

2. For this reason, if a verdict has been rendered against the weight of evidence, the court may admit a new trial, but the court will exercise this power not only with a prudent verdict, but a strict and certain verdict before transferring the case to a second jury. 3. In such circumstances, the general rule is that the decision once rendered is valid: annulment is the exception and should be an exception to rare and almost singular events. For this reason, a new procedure is granted for both parties; However, evidence should not be weighed in golden scales. 2 Hodg. R. 125; S.

C. 3 Bing. No. 109; Gilp. 356; 4 Yeates, p. 437; 3 Green. 276; 8 Selection. 122; 5 Wend.

595; 7 Wend. 380; 2 vir. 235. In contrast, weight-of-evidence considerations include all experimental results, as well as “mechanism of action” information, that is, all evidence relevant to humans, positive and negative, related to causal determination. However, caution should be exercised when assessing available human data as part of the overall weight-of-evidence process. It shall be assessed whether the determination of the strength of the epidemiological data has clearly shown the extent to which the observed association can be explained by other factors, including those that may be inherent weaknesses in the design or conduct of the study, as well as other potential explanatory factors. More than 50 years ago, a respected occupational physician named Sir Bradford Hill proposed a set of criteria to evaluate how data from different studies fit together to make a causal determination. These criteria continue to be discussed and refined, but they have largely proven their worth over time.

None of these criteria alone is sufficient to establish a causal relationship between a chemical and a disease, and only the criterion of temporality must necessarily be met to make it possible. Typically, a panel of scientific experts with broad and in-depth expertise meets to conduct such a weight-of-evidence assessment. The criteria are summarized below: The trial judge in a civil or criminal matter, whether judge or jury, must examine, assess and determine whether the evidence presented meets the standard of proof. If the trial judge meets this standard, he or she must render a verdict in favour of the plaintiff in a civil case and convict a defendant in a criminal proceeding. If the evidence does not meet the standard of proof, the trial judge must decide in favour of the defendant in a civil or criminal matter. These decisions are based on the concept of “weight of evidence,” a term used to refer to the preponderance of truth. The weight of evidence is what will convince a judge in one way or another. When assessing the evidence, scientists consider the quality of each relevant study, as well as how all the individual data fit together to create a holistic picture. There are established criteria for assessing the reliability of data derived from experiments on experimental animals (e.g. Clemisch score). Similar criteria exist to assess the quality of observational studies in humans (i.e., epidemiology).

In civil proceedings, the burden of proof on the plaintiff is the balance of the standard of proof, which means that the plaintiff must satisfy the judge that the evidence in support of his or her case outweighs the evidence presented by the defendant. Criminal proceedings, on the other hand, require that the weight of evidence proving an accused`s guilt exceed a reasonable level Doubt.In a number of jurisdictions, judges are prohibited from informing jurors of the weight to be given to the evidence. In other States, the judge is allowed to give a balanced and fair assessment of the weight he or she believes should be given to the evidence. All jurisdictions prohibit the judge from informing the jury of the weight to be given to the testimony of a witness or group of witnesses. The judge cannot declare that a particular piece of admissible evidence may or may not be entitled to weight or consideration by the jury. The judge is also prohibited from assisting a jury or violating its role in evaluating the evidence or deciding the facts. Moreover, in giving instructions to the jury, the judge does not have the right to prescribe the order and manner in which the evidence is to be considered and weighed by the jury, or to tell the jury how to consider the evidence received by the court. Therefore, the decision to take action must take into account the full weight of the available evidence, as well as the seriousness of the consequences. Assessing the causal criteria linking a chemical to a particular disease or condition is surprisingly complex. This process often involves integrating data from many studies that differ in terms of the strength of their designs, the quality of their underlying data, and even the types of adverse diseases and conditions studied.

Many scientific topics are also loaded with conflicting results, making it difficult even for the discerning reader to determine what the truth might be.