Category Archives: Firearms

Are you a gun nut?

If you are a criminal defense attorney working on serious felony cases, you need to have a good understanding of firearm function so that you can make sense of the forensic evidence in your case. The tutorials described below can help you gain the information that you need.

The University of Utah Health Sciences Library has several firearms tutorials posted which cover information about the different types of firearms and how they work, ballistics (the science of the travel or a projectile in flight), patterns of tissue injury, laboratory methods, and examination of gunshot residue.

The tutorials provide basic information, kind of like Firearms 101, as well as more technical information about trajectory, examination of firearms, and injuries caused by firearms.

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Evening at the School of Government, Part III: Firearms 101

We are excited to announce “Firearms 101,” the third program in our Evenings at the School of Government series. This series, cosponsored by the UNC School of Government and NC Office of Indigent Defense Services, consists of free presentations on forensic evidence and other criminal law topics that are designed to enhance the knowledge of criminal law practitioners. Available for CLE credit, these programs will occur after business hours at the School of Government in Chapel Hill. A social hour at a local venue will follow each presentation so that participants may continue their discussions with the speakers.

At this program, veteran defense attorney David Waters and private investigator Michael Grissom will instruct participants on firearm mechanics and functionality, projectile trajectory, and basic information about the firearm/toolmark comparison.  Using examples and images from their own cases, they will describe common issues related to forensic firearm analysis, and how defense counsel can address these through motions practice and cross-examination. They will also discuss raising challenges to a witness’s qualification as an expert and the merits of hiring a private firearms expert in a particular case.

Participants: This program is geared toward attorneys who may confront issues regarding firearms in their cases.

Location, Dates, & Times: The program will be held on Thursday, August 22 at the School of Government on the UNC-Chapel Hill campus. Sign-in is from 5:15pm to 5:30pm, at which time the program will begin. The 1.50 hour program ends at 7:00pm. Following the presentation, we welcome you to join the presenters for an informal happy hour at W XYZ bar, located in the lobby of the Aloft Hotel on Highway 54 in Chapel Hill. Directions to the Aloft Hotel can be found here.

RSVP: Registration is not required, but we ask that you RSVP via email by August 15 to Brooke Bailey, at

Fee: Free. (Because no registration fee will be charged by the School of Government, each lawyer is responsible for paying the NC State Bar for earned CLE credits at $3.00 per hour.)

CLE Credit & Certification: This program offers 1.5 hours of general CLE credit and qualifies for NC State Bar criminal law specialization credit.

Materials: Materials for this program are forthcoming and will be available under the Course Materials category on the program website ( Those who RSVP for this event will receive a confirmation email on August 19 with a link to the program materials. Please note that the materials will not be provided in hard-copy form at the program. We strongly recommend that you either bring a laptop and access the materials electronically or print and bring them with you to the program.

Directions and Parking: Directions to the School of Government may be found on our website’s visitor information page. Parking will be available in the lot adjacent to the School of Government. You will not need a parking code to enter the lot or a parking pass. (The gate opens at 5:00pm.) You will enter the building via the side entrance by the parking lot.

Additional Information: We look forward to seeing you next month.  If you have any questions or would like additional information, please contact Brooke Bailey (919.966.4227 / or Defender Educator Alyson Grine ( / 919.966.4248).

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NIJ Has Made Available New Forensic Technical Reports

The National Institute of Justice has published several reports on novel techniques that are being investigated in order to improve forensic analysis. Take a look at the reports below to learn about some of the latest techniques that are being developed and to get a forecast of what techniques you may see coming soon to a forensic lab near you!

Application of Machine Learning to Toolmarks: Statistically Based Methods for Impression Pattern Comparisons (pdf, 99 pages)

Researchers created a database of 3D striation and impression patterns on Glock fired cartridge cases, screwdriver and chisel striation patterns. They attempted to objectively associate the toolmarks with the tools that created them using principal component analysis, canonical variate analysis, and support vector machine methodology. Researchers were able to estimate an error rate for toolmark identification using these techniques and a confidence level was assigned. Researchers suggest that this methodology is a useful means of gauging the quality of a toolmark “match.”

Application of Raman Spectroscopy for an Easy-to-Use, on-Field, Rapid, Nondestructive, Confirmatory Identification of Body Fluids (pdf, 80 pages)

Research indicates that new nondestructive, confirmatory testing could identify bodily fluids, including dried fluids, with a near 100% accuracy rate using a Raman microscope equipped with advanced statistics for rapid mapping of pure bodily fluids. The research further proposes that mixed samples can be identified if the samples are not completely mixed. This nondestructive testing, if adopted in the future, could help in the preservation of crucial DNA evidence. It also offers a heightened level of confidence in the results obtained due to its confirmatory nature and level of accuracy.

Establishing the Quantitative Basis for Sufficiency Thresholds and Metrics for Friction Ridge Pattern Detail and the Foundation for a Standard (pdf, 53 pages)

Motivated by both the Daubert ruling and the findings of the National Academy of Sciences, Strengthening Forensic Science in the United States: a Path Forward (2009), researchers from multiple disciplines collaborated to develop a scientific foundation for fingerprint image quality, with a focus on latent prints.  Researchers followed an experimental approach and then performed statistical validation of their results. Their research yielded several noteworthy results, most salient being detection of unique features that can assist fingerprint examiners in drawing statistical likelihoods of a given feature. This project bolsters claims that existing methods of analysis are more of an art than a science and therefore more susceptible to human error.

Filling a Critical Need by Establishing a Fully Functioning, CODIS Dedicated Laboratory (pdf, 101 pages)

The state of Wyoming requires maintenance of a database of offender samples which historically have been processed via outsourcing to private agencies.  Through funding from both the NIJ and Wyoming State legislature, Wyoming has established their own CODIS lab to process offender samples for entry into CODIS. Currently, samples processed through the lab pass through to CODIS at a 95% success rate. Through creation of the state-run lab, sample processing time has been cut from more than two years to less than sixty days.

Implementation of a DNA Triage and Analysis System Dedicated to Increasing the Throughput of High Volume Crimes in a Forensic Laboratory (pdf, 133 pages)

Through the efforts of both the Orange County California crime lab and the Orange County District Attorney’s office, the crime lab implemented a team-oriented approach to processing DNA from property crimes. The approach employed a highly automated DNA processing method that the crime lab anticipated would free up time from the processing of property crimes, which are extremely high in volume, to devote to dealing with violent crimes. As anticipated, the new handling method decreased the turn around time on both property and violent crimes.

Taq Mutants Engineered for Forensics (pdf, 44 pages)

Researchers used novel genetically-engineered enzymes and a new protocol for DNA analysis to attempt to reduce false negative results and improve the efficiency of DNA testing. These novel enzymes and new protocol would work better with forensic samples that contain residual blood, soil, or other substances that inhibit forensic DNA analysis. Researchers found that their technique outperformed the techniques currently used in forensic DNA analysis.

Use of Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS) Methods for the Analysis of Small Particles Adhering to Carpet Fiber Surfaces as a Means to Test Associations of Trace Evidence in a Way that is Independent of Manufactured Characteristics (pdf, 77 pages)

Typically, very small particles (VSP) are ignored by forensic science. However, researchers have made the first steps towards developing a method for collecting and analyzing VSP as part of trace evidence. Researchers have successfully collected VSP from carpet fibers and demonstrated the difference between carpet fibers themselves and the VSP adhering to them. Researchers urge that VSP can prove useful in the area of trace evidence by comparing VSP from crime scenes or suspects to any items of physical evidence.

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SBI to Begin Using New Reference Standard to Assist Examiners in Identifying Cartridge Casings

A new reference standard for comparing cartridge casings has been developed by the National Institute of Standards and Technology (NIST). The standard is known as SRM 2461, Standard Casing. It was developed to assist firearms examiners by ensuring that the equipment used to match cartridge cases to those in the National Integrated Ballistic Information Network (NIBIN) database is calibrated correctly. Joseph R. John, Sr. Director of the North Carolina State Crime Lab, has confirmed that firearms examiners are to begin using this standard.

Examiners use a microscope called an Integrated Ballistic Identification System (IBIS) to view breech face marks, ejector marks, and firing pin impressions on a casing, which serve as identifying characteristics for a specific firearm once recorded in the NIBIN database. SRM 2461, Standard Casing consists of two standards, a master cartridge case with distinct markings and a digital image contained in the NIBIN database that has the same marks. If the examiner can match the standard to the digital image in the NIBIN database, the technician can have confidence that their equipment is calibrated properly. NIST claims that the new standard will allow examiners to have confidence in their methodologies and demonstrate that their work uses a national standard.

The use of the new standard casing may create some interesting opportunities for defense attorneys working with cartridge casing evidence.  For attorneys working on older cases, it raises questions regarding the absence of a national standard in the past to ensure against inaccuracies. Attorneys working on cases where SRM 2461, Standard Casing is used should keep in mind that the standard only addresses calibration. Questions about the reliability and error rate of the technique are not addressed by this calibration standard.

More information about the new standard is available here.

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Impression & Pattern Evidence Symposium – Online today!

The Impression & Pattern Evidence Symposium is taking place today through Thursday, August 9, 2012. The live program, sponsored by the National Institute of Justice (NIJ) Office of Justice Programs and the Federal Bureau of Investigation (FBI) Laboratory Division, is being streamed online here.

The agenda is available here. Topics include the latest developments and challenges to fingerprint, firearm, document, tiremark, bloodstain pattern and other types of pattern and impression evidence as well as context bias, calculation of error rate, documenting through bench notes, outsourcing lab analysis, and the way to present degree of certainty.

The entire program is available for free online streaming, so sign up and watch the sessions that are of interest to you!

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Measurement Science and Standards in Forensic Firearms Analysis Webcast – TODAY

The National Institute of Standards and Technology (NIST) is presenting a two-day conference which will address the techniques used in firearm and toolmark comparisons, the standards for this discipline, and efforts to apply more objective and quantitative measurment based techniques to this type of analysis.

This conference is being broadcast live online on July 10-11, 2012 and can be viewed here. Speakers will discuss many of the criticisms of the field of firearm and toolmark analysis that were raised in the 2009 NAS Report. Presenters are addressing what measurements can be made, standards for comparison, and what information should go in the notes section of lab reports. There is also a simultaneous transcription of the conference being produced.

There are speakers from SWGGUN, AFTE, NIST and the FBI and ATF Laboratories, as well as private labs. The conference agenda is available here. Online viewers can ask questions of the speakers using Twitter.

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Two Bullets, One Gun?

By Alyson Grine, Defender Educator, UNC School of Government

In State v. Britt, __ N.C. App. __, __ S.E.2d __ (Dec. 6, 2011) the North Carolina Court of Appeals addressed the admissibility of expert testimony regarding firearms and toolmark identification. The facts, in brief: Nancy Britt, a Wake County school teacher, was shot and killed while visiting her disabled sister in Lumberton. At the autopsy, a .25 caliber Winchester bullet was recovered from her body. The defendant, Myron Britt, was Nancy’s husband. Myron became a suspect when his brother, Dickie, told law enforcement that Myron had borrowed a .25 caliber pistol from him about five weeks before Nancy was killed. Dickie also told officers that two years previously, the same gun had accidentally discharged into a baseboard at their mother’s home. Officers recovered a .25 caliber Hornady bullet from the baseboard. SBI agents Theresa Tanner and Peter Ware compared the bullet from the decedent’s body and the bullet from the baseboard and concluded that they had been fired by the same gun.

The defendant made a pretrial motion in limine to exclude Agents Tanner and Ware’s firearm identification testimony. The trial judge decided to limit the State’s experts’ testimony to statements that the bullets were “consistent” and not allow them to testify that they had been fired from the same gun. However, after defense counsel said in opening statements that defense experts would testify as to their “opinion that you cannot make a match, that there [are] simply not enough points of comparison on the two bullets,” the trial judge reversed his ruling and allowed the State’s experts to testify to their opinions that the bullets were fired from the same gun. Their opinions were based upon the lands and grooves as well as microscopic striations and marks on each of the bullets—that is, the “toolmarks” left on the bullets from the firing of the gun. The defendant, in turn, offered the expert testimony of John Dillon, a former chief of the FBI’s firearms and toolmark unit, and William Conrad, a private consultant on firearms identification, that there were insufficient microscopic points of comparison between the two bullets to conclude that they had been fired from the same gun.

The defendant was found guilty of first-degree murder and sentenced to life imprisonment without parole. According to appellate counsel, the verdict hinged on the firearm identification testimony. “The State’s case was built on the SBI’s bullet comparison. Without the expert testimony of SBI Agents Tanner and Ware that the bullets matched, the State would have had no evidence connecting the murder with the only gun known to have been in Myron Britt’s possession.” (Appellant’s Brief, p. 13)

On appeal, the defendant argued that the trial judge erred in reversing his ruling on the motion in limine and attacked the reliability of the methodology as well as the agents’ qualifications to testify as expert witnesses. The Court of Appeals dismissed the reliability argument, stating that precedent supported the admission of expert testimony on firearms ID, and the defendant had not produced new evidence to challenge the reliability. The Court also rejected the defendant’s argument that the State’s experts were not qualified to testify. While the State did not present verification of one of the expert’s training and neither expert was a member of a professional organization, both experts explained how firearms and toolmark identification works and how they conducted their investigations. Thus, the Court found that they were better qualified than the jury to form an opinion and the trial court did not abuse its discretion in allowing them to testify.

What lessons might defenders take away from Britt? First, a trial judge may be willing to limit expert testimony about this methodology. (Sarah has posted trial counsel’s Motion to Exclude State’s Firearm Testimony in her Motions Bank as an aid.) The trial judge had misgivings about allowing the SBI firearms and toolmark identification testimony, and although he believed he was bound to admit it, he initially limited the testimony. “We should require more. But given [North Carolina] precedent…” (Tp. 4380) “[I]t’s a frightening prospect when you can’t testify to a statistical certainty under DNA analysis that a match is a certain match and you can do the exact same thing under ballistics testimony as subjective as that testimony might be. That’s concerning.” (Tp. 4381) (Appellant’s Brief, p. 14)

A defendant benefits significantly where testimony is limited to “these toolmarks are consistent with each other,” rather than “these toolmarks were made by the same gun.” Bullets or cartridge cases have consistent toolmarks, even if fired by different guns, if the guns have the same class characteristics (e.g., barrels of a particular caliber with a particular number of lands and grooves of a particular width and direction of twist), according to Professor Adina Schwartz of John Jay College of Criminal Justice, CUNY. (Schwartz has written widely on the unreliability of this forensic discipline, and Sarah Rackley has posted links to some of her articles  here.) Counsel might offer evidence of the hundreds of other firearms, with the same class characteristics as the gun in question, that were sold at the local Walmart in recent years, rendering the expert testimony merely speculative as to which gun or guns fired the bullets.

Second, if the defense succeeds in getting a ruling that limits the State’s experts to “consistency,” defense attorneys should refrain from forecasting or introducing defense expert testimony that the resemblances between the individual characteristics of toolmarks were not sufficient to justify an identification. Such testimony may open the door for the court to retreat from its consistency ruling and allow prosecution experts to testify to an identification. Meanwhile, according to Professor Schwartz, defense expert testimony is not likely to offer any advantage: “In most cases, defense experts will only be willing to testify to an ‘inconclusive’; such testimony adds nothing where a pre-trial ruling limits prosecution experts to testifying that marks on ammunition components are ‘consistent with’ each other because firearms and toolmark examiners use both terms  ‘consistent with’ and ‘inconclusive’ to mean that it is not possible to conclude that marks were made by the same gun, but only that the marks were made by a gun(s) with the same class characteristics.”

In rare cases, defense experts may be willing to go beyond an “inconclusive” and testify that the lack of resemblance between individual characteristics of the toolmarks is so great that ammunition components can be excluded from having been fired from the same gun. Even in this instance, however, it is generally inadvisable for the defense to put on its own testimony about individual characteristics. Professor Schwartz cautions that on cross, the prosecution will be able to bring out the fact that most firearms and toolmark examiners (including FBI examiners) do not exclude on the basis of individual characteristics. Additionally, the prosecution may point out the absence of any objective criteria for how much difference between individual characteristics is needed for an exclusion. Opening the door remains a concern as well; a trial judge is not likely to allow defense experts to testify that individual characteristics are so different as to justify an exclusion without allowing prosecution experts to testify that the individual characteristics are so similar as to justify an identification.

By contrast, Professor Schwartz advises that the defense should put on expert testimony, even if there is a pretrial consistency ruling, if the disagreement between defense and prosecution experts extends to whether toolmarks on ammunition components have the same class characteristics (in other words, whether the ammunition components could have been fired from the same type of gun): “Defense expert testimony about class characteristics will not open the door for prosecution experts to testify that individual characteristics justify an identification.”

A third important takeaway from Britt is that defenders should not give up on the reliability argument. Under Howerton v. Arai Helmet, Ltd., when presented with “compelling new perspectives on otherwise settled theories or techniques,” a trial court can look beyond precedent to determine whether an expert’s area of testimony is sufficiently reliable. 358 N.C. 440, 597 S.E.2d 674 (2004)(Appellant’s Brief, p. 25) In Britt, the defense introduced case law and law review articles discussing the unreliability of firearm and toolmark evidence. (Appellant’s Brief, p. 21) However, the Court of Appeals appeared to require a greater showing of the defendant, holding that “[i]n the instant case, however, defendant did not introduce any ‘new’ or ‘compelling’ evidence to the trial court.” Slip op p. 10. Defenders who wish to challenge the reliability of firearms toolmark identification may therefore need to introduce evidence of unreliability beyond written materials such as case law and law review articles. However, the reliability argument was undermined in Britt by the fact that the defense put on experts who had relied on the same or similar methodology as the State’s examiners.

Furthermore, in a previous post on expert testimony, I commented that following legislative changes to N.C. Evidence Rule 702(a), “Court actors should not presume that a method of proof that was deemed sufficiently reliable under the former North Carolina rule and Howerton will be admissible under the amended rule.” S.L. 2011-283 (H 542), as amended by S.L. 2011-317 (S 586), effective for actions arising (that is, offenses occurring) on or after October 1, 2011. The Britt case illustrates that it is not unusual for firearms and toolmark examiners to disagree about whether resemblances between individual characteristics are sufficient to show that ammunition components were fired from the same gun, giving rise to an argument that opinion testimony about whether toolmarks match does not meet the requirements of revised Rule 702(a): “The absence of an objective criterion for when the resemblances between toolmarks are sufficient for a match means that when examiners disagree, the discipline of firearms and toolmark identification has no resources for determining who is right,” according to Professor Schwartz.

Finally, while a consistency ruling is a victory for the defense, defenders should not give up on arguing for total exclusion of firearms and toolmark identification testimony because of the risk of unfair prejudice and confusion. Professor Schwartz advises: “The problems with allowing prosecution experts to testify that ammunition components were fired from a gun or guns with the same class characteristics are, first, there is no data on how many guns share the same class characteristics; second, jurors are likely to confuse testimony that the marks on ammunition components are consistent with testimony identifying ammunition components as having been fired from the same gun.” This gives rise to an argument under N.C. Evidence Rule 403 that the probative value of testimony about toolmarks is outweighed by the dangers of unfair prejudice and confusion of the jury and must, therefore, be excluded.

In writing this post, I drew on the brief by David Neal, counsel for the defendant-appellant, and notes by Professor Adina Schwartz of John Jay College of Criminal Justice, CUNY. I thank them for their insights.

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