When is evidence reliable

The evidence would be inadmissible for that purpose, because it is hearsay. It might be admissible to prove why the dispatcher sent an ambulance to the Bates Motel that night, assuming that fact would need to be proven in the case. But it would not be admissible to prove that the defendant murdered a guest at the motel. There are other reasons for which evidence of this type might be admissible or inadmissible.

Of course, there are exceptions to the hearsay rule, discussed below, as there are to every rule of evidence. The point is that any type of evidence, including hearsay, might be admissible for one purpose but not for another. In addition, decisions about evidence may not be at all simple. More than one rule may indicate that a certain item is inadmissible, while exceptions or other rules may indicate that it is admissible.

Every item of evidence must be carefully analyzed. The general rule is that all relevant evidence is admissible and irrelevant evidence is inadmissible. So, to be admissible, every item of evidence must tend to prove or disprove a fact at issue in the case. If the evidence is not related to a fact at issue in a case, it is irrelevant and is, therefore, inadmissible. There are four basic types of evidence:. Generally speaking, the rules regarding the admissibility of evidence in civil proceedings are the same as the rules regarding the admissibility of evidence in criminal proceedings.

There are, of course, as always, exceptions. One example is the doctrine of estoppel, a technical and complicated rule of evidence that applies only in civil proceedings.

In criminal cases, there are special rules regarding confessions, because of the Fifth Amendment to the U. As a practical matter, this means that, before a confession can be admitted into evidence to prove the guilt of the defendant, the judge must hold a hearing to determine whether the defendant made the confession voluntarily. Of course, the jury is not allowed to be present during this hearing. A jury would never hear the confession, unless the judge decides that it was made voluntarily.

There is a complicated set of exceptions that apply to character evidence regarding the defendant and the victim in criminal trials. The exceptions do not apply in civil trials. This is just one example of a difference in the rules of evidence for civil and criminal trials. Different kinds of evidence are presented in civil trials and in criminal trials because of the different kinds of facts that need to be proven in the two different types of cases.

There is extensive law about eyewitness testimony and whether it is evidence that is reliable and can be trusted by a jury given the psychology of memory and its fallibility. This is because eyewitness testimony is often very critical in criminal cases when a person claims to have seen the perpetrator commit the crime. In civil cases, the authentication of documents is more often an issue as documents may be more important in proving the facts of the case. Epidemiological studies are also of this type and often identify correlations between phenomena.

Observations without interventions can only disprove a prediction or hypothesis. That is, if no correlation is found between two variables it is most unlikely that one causes the other. Such observational studies of associations must be viewed with great skepticism; they can only give clues to causal relationships. Interventional studies where a variable is deliberately altered or there is successful predictive testing of a model see below are necessary to demonstrate causal relationships between phenomena.

Recorded results of interventional experimentation that is appropriately designed and carried out Results of interventional experimentation allow choices to be made between ways of doing things. An example is how best to treat disease where randomized, controlled trials compare one treatment with a placebo or another treatment.

The experiments must be designed appropriately and performed diligently for conclusions to be valid. Important points in design are randomization of treatment groups and their treatment; unbiased observers who do not know which treatment is being given to a particular patient plus patients who do not know what treatment they are receiving double-blinding ; accurate and appropriate end-points of the success or failure of treatment and appropriate comparisons e.

Above all, the appropriate controls must be used so that like is compared with like and every attempt must be made to avoid bias in selection of subjects. The statistics applied to such clinical experimentation were originally developed by R. Fisher for testing various interventions to improve crop yields at an agricultural research station in the UK.

Results from randomized, controlled trials are the gold standard of evidence-based medicine. Repetition and confirmation of the experiments as in 8 Replication of results is an important aspect of science that is sometimes forgotten. Although there can be statistical variability, similar experiments should yield similar results. If the results differ between experiments, reasons for the difference should be sought. Systematic reviews meta-analyses of randomized, controlled trials are an attempt to quantify the degree of reproducibility of interventional experiments.

Successful predictions based on a model derived from recorded systematic observations Being able to predict eclipses and the movements of the tides are remarkable achievements that took centuries to develop.

The current prediction of tides includes something like 60 variables and the digital computer has been a boon. The description of gravity by Newton and the realization that the moon exerted gravity was an important step in understanding tides, but so were fluid dynamics as described by la Place. The point is that interventional experimentation could not be done, but extremely accurate and successful predictive models resulted from the systematic observations and testing of various models of both the heavens and the seas.

Nothing in medicine can be predicted with the accuracy of tides or eclipses, for our understanding of bodily function is very superficial; our models are inadequate for accurate prediction. Even when the model developed by a biologist leads to Nobel Prizes as in the description of how a nerve impulse is conducted ion fluxes , the double helix of DNA, or how blood vessels dilate by producing nitric oxide, the described model is brilliant, but still inadequate for all but simple predictions of biological behavior.

This strongly suggested that the then current models of the atom were substantially correct. The ultimate, dramatic test of theory was to produce an atomic explosion. As stated previously, this degree of understanding of a model is not present in any system of biology; such systems are very complex and our knowledge quite superficial.

Therefore physician-scientists cannot predict the future behavior of a biological system except in an approximate way; biological systems are more complex than those that produce even atomic explosions. The success in achieving an atomic explosion, however, also changed how science is funded and organized. It led to the development of the National Institutes of Health in the US and to the system of applying for research grants that we have today.

But that is another story. Epilogue Human behavior is complex; much of it is learned by rote and almost automatic or intuitive, without conscious thought. The hierarchy of evidence as discussed above would not apply to decisions made on that basis but only to decisions made on an intellectual basis.

It might be useful, however if more of our decisions were made in the latter context, particularly the important ones. Agency for Health Care Policy and Research. Acute pain management: Operative or medical procedures and trauma. Clinical practice guideline No. Harbour R, Miller J. Scottish Intercollegiate Guidelines Network Grading Review Group, A new system for grading recommendations in evidence based guidelines.

BMJ ; Competent and reliable evidence is evidence i which has been generated and evaluated by persons qualified by training and experience to do so, using procedures generally accepted by others in the profession, and ii for which it can fairly and responsibly be concluded by qualified experts that there is reasonable assurance of the accuracy and reliability of the results of a test for the intended use.

Lynn Bush, Bucks County, reported that the county is nearing the end of their Comprehensive Plan update. Competent and reliable evidence means tests , analyses , research , studies , or other evidence based on the expertise of professionals in the relevant area , that have been conducted and evaluated in an objective manner by qualified persons , using procedures generally accepted in the profession to yield accurate and reliable results ; and.

Sample 1. Sample 2. Just laws rely on truth and right. But to recognize truth and right, we need reliable evidence to show what is true and right. Sometimes this can be meaningfully corroborated by disproving something as false or wrong.

Over the past centuries, the search for truth in science has been formalized into the process known as the scientific method, whereby theories are developed and tested according to a generally-accepted standard. In a similar fashion, the legal profession operates by what is known as the Rules of Evidence.