RaquinMercer Law Offices
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Using Our DNA / Forensic Expertise For Creative Evidentiary Solutions

Challenges to the use of DNA/forensic science evidence in criminal trials, appeals and post-conviction proceedings is a core practice area at RaquinMercer LLC. Steve Mercer’s litigation experience in private practice and as the Chief Attorney for the Forensics Division of the Maryland Public Defender has focused on DNA/forensic science. Steve Mercer is an associate member of the American Academy of Forensic Sciences.

Now he has partnered with Isabelle Raquin to provide DNA/forensic science solutions for defense attorneys. Steve and Isabelle know that defense attorneys must aggressively challenge the admissibility and weight of DNA/forensic science that is error-prone, premised on highly subjective judgments, and vulnerable to bias and exaggerated claims of uniqueness. In addition to providing our clients with outstanding defense representation based on cutting-edge DNA and forensic expertise, Steve serves as a consultant to his criminal defense colleagues on cases involving complex evidence.

Contact RaquinMercer LLC today for information on consulting with Steve and Isabelle about discovering problems with DNA/forensic science in your case and developing solutions as robust as your need.

The State Of Forensic Science In The United States

Over the past decade, the scientific community has produced two comprehensive and sharply critical assessments of the state of forensic science in the United States. How should defense attorneys respond? What new pathways of litigation will leverage this substantial increase in the scientific knowledge base concerning errors in DNA/forensic science? Will the litigation avenue you select succeed in your case?

One answer is certain: invoking the NAS or PCAST reports – which contain authoritative criticism of the reliability of a wide range of DNA/forensic science disciplines – will not compel the exclusion in a criminal case of a method prone to error. To mount an effective challenge, the defense ordinarily must identify actual problems with the method as applied to the evidence tested in a particular case. This practical reality means defense attorneys must aggressively pursue complete discovery. Yet formulating a comprehensive discovery plan is a substantial undertaking itself that requires, at a minimum:

  • Expertise with the discipline at issue; the analyst(s) and laboratory testing the evidence
  • Knowledge of the expected documentation associated with an analysis and interpretation
  • Recognition of the customary and ordinary language and assumptions used in reports versus unusual terms, caveats or unreasonable assumptions
  • Awareness of the gaps in a laboratory’s standard protocols for documenting the results of bench work that can obscure anomalies in data collection procedures
  • Knowledge of the limitations of information contained in pass/fail reports of proficiency reports and where to find administrative and technical errors in these tests
  • Knowledge of how accrediting and licensing bodies conduct audits and laboratory’s manage other quality assurance measures that can include documentation of errors, anomalies or issues in the laboratory
  • Experience interviewing analysts and onsite reviews of case-related documentation

Discovery Is Crucial In Criminal Cases

This is a steep learning curve, but obtaining full discovery increases the likelihood that actual problems with the application of a method at issue to the evidence in your case will be identified. Further, without full discovery, the defense cannot evaluate the need or fit for a subject matter expert. An essential part of a successful challenge is litigating discovery. Only then can problems be identified and litigation solutions developed.

DNA/Biological Evidence

The most common types of biological evidence include blood, saliva, skin cells/perspiration (“touch DNA”) and semen. Typically, the dual aim of the testing is to indicate the type of biological evidence and provide sufficient samples of biological evidence to allow DNA profiling. DNA is touted as the “gold standard” but not all DNA is the same. The relentless demand for DNA evidence in criminal prosecutions and swifter, more sensitive testing methods create opportunities for error in source attribution and the identification of bodily fluids.

Weapons Evidence

Weapons evidence consists of firearms (handguns/rifles/shotguns), ammunition (spent casings, fired projectiles, bullet fragments, and unfired bullets), gunshot residue (GSR) tests, and knives. The discipline of firearm/toolmark comparisons and related gunshot residue testing was created by law enforcement – not the scientific community. Like other methods developed to produce evidence for use in criminal prosecutions, the discipline relies heavily on an examiner’s subjective judgment that is formed using a methodology that lacks foundational reliability.

Fingerprint Evidence

Fingerprint evidence consists of comparisons between “10-prints” (fingerprints collected from a known person) and latent prints (only partial prints of one or more fingers collected from evidence associated with a crime). Similar to other pattern impression disciplines created by and for law enforcement, there are gaps in the methodology when applied to complex real-world conditions (including partial/degraded latent prints and cues from case-related communications and automated identification systems) that can bias an examiner’s subjective judgment.

Drug Evidence

Drug evidence includes drugs (PCP, heroin, marijuana, cocaine, methamphetamine, and others), and drug paraphernalia (pipes, spoons, papers) found at a scene, on a person, or used in a transaction. The scientific community has demonstrated the validity of certain drug testing methods, such as gas chromatography/mass spectrometry (GC/MS) or thin-layer chromatography (TLC) when used in accordance with validated protocols. The existence of reliable protocols does not however, mean the protocols were actually followed by a law enforcement laboratory in real-world conditions (high throughput of samples, poor oversight/review, training, pressure from trial deadlines) to real-world evidence. Testing of residue and synthetics are particular areas of concern.

Pattern Impressions Evidence

Pattern impressions evidence includes bitemark impressions/comparisons, shoeprint impressions, tire tracks, and tool marks. Pattern impression evidence is highly prone to false positives, misidentifications, and exaggerated claims of weight. The scientific community has generally accepted that bitemark impression evidence is unreliable, but some courts continue to admit it.

Trace Evidence

Trace evidence describes the category of evidence that includes small, possibly microscopic, material. It covers a wide variety of evidence, but most typically involve hair and fibers (natural and synthetic). A microscopic examination for optical similarities between question hairs or fibers and known hairs or fibers is a methodology unique to law enforcement, and the process is highly vulnerable to examiner bias, error, and exaggerated statements about weight and uniqueness. Gas chromatography/mass spectrometry (GC/MS) has long been the accepted method for qualitative analysis of synthetic fibers (typically carpet fibers) but the collection and analysis of trace evidence and the reporting of results can be susceptible to error due to contamination, transfer, and bias, i.e., cherry-picking consistent data while ignoring inconsistent data.

Digital Evidence

Electronic and printed data include documents and electronics (computers, cell phones, GPS), as well as video and audio recordings and other forms of surveillance (facial recognition). Digital evidence is highly vulnerable to errors because the objective of a forensic analysis of digital evidence is not a purely qualitative undertaking. The purpose is to obtain evidence that implies the actions of a person associated with the data. Examiners may not account for systemic error in data collection. This problem is compounded by tunnel vision and a failure to consider alternative explanations for the data.

Medical And Pathology Evidence

Medical and pathology evidence include cause and manner of death, nature and extent of injuries, and accidental/non-accidental causes of trauma. Because the cause and manner of death or injury are inherently opinions, subjective judgment is required to formulate these legally non-binding conclusions. Often the circumstances of a death or injury, in particular the history provided by a caregiver, inform the degree of certainty for a doctor’s judgment – rather than empirical data establishing the foundational validity of an underlying medical or scientific phenomenon.

Contact Us For Your Defense Needs In Maryland & Washington, D.C.

Not only do we strive to provide excellent legal services, but we also want to ensure you understand all of your available legal options. We enjoy the fight inherent in criminal cases and love to challenge every aspect of our clients’ cases, every step of the way. We thrive on the complexity of cases involving forensic science; no case and no science is too difficult for us to comprehend or too hard to contest. Contact us today to schedule a confidential consultation.

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