How Federal Defense Lawyers Use Forensic Experts to Fight Criminal Charges
Contents
- 1 How Federal Defense Lawyers Use Forensic Experts to Fight Criminal Charges
- 1.1 Scrutinizing the Collection, Handling and Testing of Evidence
- 1.2 Questioning Relevance and Probative Value
- 1.3 Advancing Alternate Theories of Forensic Evidence
- 1.4 Using Discovery to Uncover Flaws in Lab Reports
- 1.5 Seeking Evidence Exclusion Based on Constitutional Violations
- 1.6 Employing Courtroom Theatrics to Discredit Forensics
- 1.7 Leveraging Past Forensic Frauds and Errors
How Federal Defense Lawyers Use Forensic Experts to Fight Criminal Charges
Federal defense lawyers rely on forensic experts to challenge all types of scientific evidence presented by prosecutors. From DNA and fingerprint analysis to computer forensics and ballistics, forensic evidence often plays a pivotal role in criminal trials. Retaining qualified forensic experts is essential for defense attorneys to rebut flawed forensic proof and raise reasonable doubt about defendants’ guilt.
Scrutinizing the Collection, Handling and Testing of Evidence
One of the first things federal defense lawyers do is thoroughly examine how evidence was collected, stored, and tested by police agencies and crime labs. Even minor gaps in the chain-of-custody or deviations from proper protocols can undermine the reliability of forensic proof.
For example, in a widely-publicized Houston drug case, testing revealed a lab technician who handled evidence had cocaine in her system. Such contamination could obviously compromise test results. Defense lawyers will highlight similar issues regarding sloppy evidence handling to show juries why forensic conclusions may be unreliable.
Defense experts also review the specific testing methodology used by government analysts. Many crime labs still use outdated techniques that have been scientifically debunked. For example, microscopic hair analysis has been proven to be junk science with error rates up to 90% in some older cases. Retaining independent experts to critique forensic techniques is key.
Questioning Relevance and Probative Value
Federal defense attorneys also challenge forensic proof by disputing its relevance and probative value to the actual charges. For example, DNA or fingerprints showing a defendant was merely present at some point does not necessarily prove they committed a crime. Partial prints that could match thousands of people may have negligible probative value.
Pointing out such limitations allows defense lawyers to minimize the weight jurors assign to forensic evidence compared to more compelling proof. Even rock-solid DNA hits can be consistent with innocent explanations like prior consensual contact. Defense experts propose alternate theories that resonate with common sense.
Advancing Alternate Theories of Forensic Evidence
Simply attacking forensic proof often backfires by making defendants look guilty and their lawyers appear desperate. Savvy defense attorneys proactively advance plausible explanations that account for damning forensic evidence while still maintaining innocence.
For example, the presence of a defendant’s blood or DNA at a murder scene could have innocently gotten there days or weeks before the actual killing. Crime labs have even accidentally switched DNA samples between unrelated cases, raising the possibility evidence was contaminated or deliberately planted.
Brain injuries, mental illness, false confessions, misleading eyewitnesses, and evidence tampering can also explain why forensics implicates innocent defendants. Part of mounting an aggressive defense is thinking creatively about reasonable doubt scenarios.
Using Discovery to Uncover Flaws in Lab Reports
Before trial, federal defense lawyers employ discovery to obtain all documentation related to forensic testing from police and government labs. Analyst bench notes, communication records, proficiency testing, standard operating procedures, and data relied upon for conclusions are all discoverable material.
Reviewing the paper trail behind lab reports allows defense experts to spot discrepancies, mistakes, uncertainty, or even evidence of outright fraud. For example, examiners may have deviated from protocols in ways that undermine reliability. Or their testimony in other cases may reveal overstatement and bias. Discovery provides a treasure trove to undermine forensic proof.
Seeking Evidence Exclusion Based on Constitutional Violations
If evidence was obtained illegally by police through Fourth Amendment violations or coercive interrogations infringing Fifth Amendment rights, federal defense lawyers can seek suppression under the exclusionary rule.
For example, warrantless searches lacking probable cause frequently produce evidence ruled inadmissible. Any forensic proof derived from or tainted by constitutional violations gets excluded when defense lawyers file successful motions.
Suppression of illegally-obtained evidence is one of the most effective tools to counter damning forensics.
Employing Courtroom Theatrics to Discredit Forensics
Courtroom drama during cross-examination is an age-old tactic defense lawyers use to visually imprint doubt about forensic conclusions. Simple props like magnifying glasses, rulers, protractors, strings, and chalk allow defense attorneys to expose key measurement errors made by crime scene analysts that render findings totally unreliable.
Other cheap props like blood vials, DNA swabs, fingerprint powders, and chemical testing reagents powerfully convey gaps in evidence collection, handling errors, and flaws in lab analysis. Juries find such theatrical, interactive demonstrations far more compelling and memorable than dry verbal exchanges.
Leveraging Past Forensic Frauds and Errors
Lastly, federal defense lawyers remind juries of the many past scandals involving falsified lab results and faulty forensic techniques that wrongfully convicted innocent defendants. Expert witness lies from the likes of Fred Zain, Joyce Gilchrist, and Annie Dookhan exposed the alarming fallibility of forensics.
Publicizing such failures through litigation has led to ongoing scrutiny, major reforms, and improved standards. But human bias and mistakes still persist. Pointing to past systemic failures allows juries to appreciate how even the most air-tight forensic proof could be totally wrong.