An analysis of the breakdown of evidence in forensic science

Legal burden of proof and Philosophic burden of proof The burden of proof is the obligation of a party in an argument or dispute to provide sufficient evidence to shift the other party's or a third party's belief from their initial position.

An analysis of the breakdown of evidence in forensic science

This means that there is no effect on a breath test or analysis caused by mouth alcohol: So in summary, the use of an electronic cigarette by a subject just prior to their breath testing or analysis will have no effect whatever on the instrument reading so produced.

This fact has been proven by way of relevant practical experimentation at Lion: When I calibrate a fuel cell-based breath analysis instrument, must I always do so at the legal limit for driving, or at my cut-off level for employees, whichever is relevant?

Because the response of the Lion fuel cell sensor to alcohol vapour is linear over a wide alcohol concentration range, you can use an alcohol vapour standard at any value to calibrate the instrument.

However, for the greatest accuracy, we do not recommend the use of a standard with an alcohol level lower than 0.


Will smoking affect the result of a breath test using a Lion instrument? This delay period is generally more than adequate as, in most cases, any significant traces of smoke are gone from their lungs in under HALFa minute.

On no account ever allow raw tobacco smoke to enter the instrument. This could possibly damage the sensitive alcohol sensing system within it. Untreated or poorly treated diabetic persons may generate a chemical substance called acetone in their breath.

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However, all Lion instruments use analytical technology that is unaffected by breath acetone, so that the reading obtained will be due to alcohol only. Can an asthmatic person supply a breath specimen into a Lion breathalyser; and if they can, would this condition affect their final breath alcohol reading?

Asthma is a variable condition, which during an attack results in the fine airways deep in the lungs becoming restricted: Fuel cell based instruments are certainly unaffected by hydrocarbons such as petrol; and by ketones, as may be present in the breath of a person such as a diabetic, or someone on a low-carbohydrate diet.

And even if they did, they would still be impaired anyway! These are designed to meet current national and international specifications [such as OIML R], which effectively require them to be specific to ethanol.

Untreated or poorly treated diabetic persons may generate a chemical substance called acetone in their breath. This is a by-product of the breakdown of fat, which the body uses as an energy source if they lack the insulin that is needed metabolise the usual energy source - sugar. Evidence, broadly construed, is anything presented in support of an assertion. This support may be strong or weak. The strongest type of evidence is that which provides direct proof of the truth of an assertion. At the other extreme is evidence that is merely consistent with an assertion but does not rule out other, contradictory assertions, as in circumstantial evidence. DNA Evidence Basics. DNA collection and analysis gives the criminal justice field a powerful tool for convicting the guilty and exonerating the innocent. These pages provide general information on a wide range of topics. Forensic Science National Institute of Justice, Seventh Street, NW, Washington, DC

This is achieved by multi-filtering infrared optical techniques, in conjunction with the controlling analytical software. Will medicines affect the breath alcohol reading in a Lion breathalyser instrument? Alcohol is a volatile chemical: Any medicine taken in tablet form is plainly a solid, which cannot evaporate into the air, so it is not in the breath, so it cannot affect the alcohol reading.

Any liquid medicine that contains alcohol will plainly cause some increase in the breath level. However, provided the user complies with the stated dose, then such an elevation will be both very small and quite temporary.

Also, the analytical technology used in Lion instruments be unaffected by practically all other liquid ingredients in the medicine.

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So in general, NO, medicines cannot influence breath alcohol readings as obtained using Lion breathalyser instruments.

I have seen some very low cost breath instruments on sale on the internet, and in petrol stations: Unlike Lion instruments, which all use fuel cell analytical technology, these products almost invariably use semi-conductor sensors for the actual alcohol analysis.

An analysis of the breakdown of evidence in forensic science

Although low in cost, these semi-conductor sensors suffer from a number of technical limitations and, as such, are not used in the equipment that is used by any Police Force.

Is the or instrument sufficiently accurate to produce alcohol analysis evidence for use in disciplinary proceedings? Because this breath has never been in close contact with the blood, it cannot be used in any quantification process.

It is, however, a very reliable method of determining whether the subject has any alcohol in his or her body. Is it possible for the subject to catch a disease though the use of a Lion breath instrument, such as by inhaling germs left behind from the previous user?

But further, the highly acidic conditions inside the fuel cell will destroy any bacteria that may have entered the instrument, so the next person is quite safe from the transfer of any potentially pathogenic material; even if they were to suck back on the mouthpiece.

This too prevents the transfer of any bacteria that may still be present inside the instrument after the last subject from being transferred to the next in the event they suck-back. Also, the design of the sampling end-cone is such that most of the breath passes to its side, rather than back to the subject.


Tests carried out have shown that there is no risk of disease-agent transfer in this way either. There is no proven record of anyone ever having contracted any disease through breath analysis by means of a Lion instrument.

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This groundbreaking series examines how cutting-edge forensic techniques such as DNA and fiber analysis are used to track down ruthless criminals. Get the latest science news and technology news, read tech reviews and more at ABC News. Publisher of academic books and electronic media publishing for general interest and in a wide variety of fields.

Evidence collection and preservation are extremely important to the crime scene process. 1 FINAL TECHNICAL REPORT Application of Laser-induced Breakdown Spectroscopy to Forensic Science: Analysis of Paint and Glass Samples Michael E. Sigman.

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