The ratio of blood-alcohol concentration (BAC) to breath-alcohol concentration (BrAC), which is commonly referred to as the blood/breath ratio (BBR), is an important concept in forensic science and legal medicine. For example, the BBR serves as the calibration factor used when a breath-alcohol test result is converted into the coexisting BAC for clinical, research, and forensic purposes. Furthermore, when legislative bodies established statutory BrAC limits for driving, they divided the statutory BAC limit by an assumed population average BBR, hence BrAC = BAC/BBR. However, jurisdictions opted to use different BBRs when calculating statutory BrAC limits for driving, and values of 2000:1, 2100:1, 2300:1, and 2400:1 were used in different countries. Under in vitro conditions, the blood/air partition ratio of ethanol can be determined with high precision (coefficient of variation CV ~2%), whereas in vivo the BBR of alcohol depends on numerous physiological factors, such as lung physiology, breathing pattern, and other biological variables; BBRs in vivo have CVs ranging from 8-12%, depending on the type of breath analyzer used. BrAC increases during a prolonged exhalation into an evidential breath-alcohol analyzer and the BBR therefore decreases as a person reaches a vital capacity exhalation. The BBR of alcohol also depends on whether arterial (A) or venous (V) blood samples were used for ethanol analysis, because A-V differences are continuously changing during the absorption, distribution, and elimination stages of the blood-alcohol curve. This article reviews the historical background and wisdom of assuming a constant BBR of alcohol for legal purposes when breath test results are used as a proxy for venous BAC. Discussion and debate about a person's BBR should be irrelevant in those jurisdictions that enforce a statutory BrAC limit for driving.
Driving under the influence (DUI) of alcohol and/or illicit drugs has been shown to increase the risk of involvement in road traffic collisions. Thanks to the scientifically proven link between blood alcohol concentration and impaired driving ability, a broadly accepted legislative framework has been established and is now widely adopted across the globe. In contrast, less is known about the effects of illicit drugs, and a clear correlation between blood drug concentrations and driving performance has been defined by some authors as a "mirage". In this review, we examine the advantages and limitations of current legislative initiatives regulating DUI of psychoactive drugs. The predominant approaches employed are "zero tolerance", "legal limits", and "impairment assessment". We discuss the distinctions among these methods, focusing on their implications for balancing citizens' rights and public safety. Additionally, we address the pre-analytical, analytical, and post-analytical challenges associated with the implementation of each legislative framework. The application of these three approaches is also discussed in light of recent changes in drug policies observed in many countries, including the decriminalization of certain substances, such as cannabis, and the growing prevalence of drugs prescribed for medical purposes. In conclusion, due to the absence of a robust scientific foundation, determining the most appropriate approach among the three remains challenging. The choice of method is primarily influenced by the government's policy priorities, which may emphasize either the protection of citizens' rights or the promotion of road safety.
Questioned document examination is one of the most challenging tasks in the field of forensic science. Examining the document without destroying its integrity is difficult in such cases. Microscopic examination is a noble and mostly non-destructive approach in document examination. It enables the examiner to visualize the evidence in the document, which would have been otherwise difficult with unaided eyes. The purpose of the study was to establish the importance of microscopic examination in document examination. A critical review of 60 years, from 1963 to 2023, of various research papers from different journals has been conducted. Applications of various microscopes including stereo microscopes, digital microscopes, scanning electron microscopes (SEM), and atomic force microscopes (AFM) were reviewed. Compared to the basic examinations performed before the year 2000, there was a remarkable evolution involving complex examinations with more precise results after the year 2000. Microscopy helped solve almost all kinds of problems involved in document examination. Among all microscopes, the stereo microscope was found to be a prominent tool in document laboratories. Certain limitations were also listed for microscopic examination over spectroscopic methods. However, microscopes have been the tool of choice for forensic document examiners.
Fingerprints are well-known and reliable means of identification in forensic sciences and security technology. Literature that covers the history of fingerprints often refers to ancient Chinese knowledge on this topic. The earliest use of fingerprints, indeed, can be traced back to the Zhou dynasty (, 1046-256 BCE), and the first documented use of crime scene fingermarks dates back to the Qin dynasty (, 221-206 BCE). During the Tang dynasty (, 619-907 CE) and Song dynasty (, 906-1279 CE), fingerprints were widely used on contracts, divorce papers, and other legal documents. However, many of the literature references are inaccurate or obsolete, so this paper reviews some of the original sources from the Tang and Song periods that are now publicly available, thus attempting to investigate the Chinese use of fingerprints.
This article traces the development and present status of legislation pertaining to driving under the influence of alcohol (DUI) and other drugs (DUID) in the United Kingdom (UK). The Road Safety Act of 1967 represented a paradigm shift in the way that traffic offenders were prosecuted for driving after consumption of alcohol. This new legislation defined punishable concentrations of alcohol (ethanol) in samples of the driver's blood (80 mg%) or urine (107 mg%). The creation of these statutory concentration limits meant that it was no longer necessary to prove that a suspect was under the influence or impaired by alcohol at the time of driving. Also in 1967, a police officer in uniform was permitted to administer a roadside breath alcohol screening test to help make a decision whether a suspect should be arrested for further investigation. In 1983, the British government introduced a statutory breath alcohol concentration limit of 35 μg/100 mL and evidential quality breath analyzers were approved for use by the police as an alternative to sampling blood or urine for analysis. Evidence of driving under the influence of drugs other than alcohol depended on the results of a clinical examination and questionnaire done by a police surgeon. This was supported by evidence presented by the arresting police officers or other witnesses. In 2015, a radical change occurred in the legislation pertaining to drug-impaired driving where instead of relying on clinical evidence of impairment, concentration limits in blood for 17 psychoactive substances were defined by statute. These consisted of eight commonly encountered recreational drugs of abuse and nine prescription medications (opiates and benzodiazepines), all classified as controlled substances.
