Opinion ID: 1998034
Heading Depth: 1
Heading Rank: 5

Heading: objections related to dna evidence

Text: We next consider Williams's contention that the trial judge improperly restricted his cross-examination of an expert witness who testified for the State regarding the DNA testing that linked Williams to the crime scene. The DNA evidence, produced by Cellmark Diagnostics, Inc. of Germantown, Maryland, consisted of test results comparing the DNA from a sample of Williams's blood to that in epithelial cells found on a drinking glass in the kitchen of the Gilbert/Trias home. Melissa Weber, the senior molecular biologist at Cellmark who performed the tests, testified that the test results showed that the types of DNA obtained from the glass were the same types as those found in the blood sample obtained from Williams. Weber also testified that Gilbert and Trias were excluded by the tests as sources of the DNA. Weber testified that the DNA evidence was obtained using a DNA testing procedure called polymerase chain reaction (PCR). PCR testing differs from a more established form of DNA testing, known as restriction fragment length polymorphism (RFLP). Weber stated that while RFLP testing can provide a very specific match between two samples, PCR testing can only narrow down a potential number of donors to a certain group. She explained that while RFLP testing requires a large sample of material, PCR testing can be done on much smaller samples because it isolates and then replicates the DNA before typing it. [6] Before trial, Williams moved to exclude the PCR test results. A two-day hearing was held during which the court heard expert testimony concerning PCR testing and whether it had attained general acceptance in the scientific community. See Reed v. State, 283 Md. 374, 381, 391 A.2d 364, 368 (1978). After the hearing, the trial judge denied Williams's motion to exclude the DNA evidence, concluding there is a general acceptance in the relevant scientific community as to the reliability of PCR.... Before addressing Williams's challenge to the admissibility of the PCR evidence, see Section V(B), infra, we shall consider his contention that the trial judge improperly restricted his attempts to cross-examine Weber concerning the frequency of errors and contamination occurring during PCR testing at Cellmark. On direct-examination, Weber was asked by the State to describe the procedures for PCR testing, and the steps taken to ensure that technicians at Cellmark properly perform the tests. Weber explained that Cellmark technicians undergo blind proficiency tests given by independent forensic associations to determine if the lab's procedures are working properly. Weber testified that Cellmark had no errors in any of the PCR proficiency tests the laboratory performed. During cross-examination, defense counsel asked Weber about testing errors and incidents of contamination that occurred apart from the proficiency tests. Specifically, defense counsel queried whether any tests at Cellmark ever had been contaminated from testing solution accidentally spilling over onto a sample and polluting it. Weber acknowledged that she could think of at least one occasion where such spill-over contamination of a sample had occurred while she was performing a test. Defense counsel then sought to ask Weber how often such errors occurred at Cellmark generally, and the State objected on the ground that the question was irrelevant. At a bench conference, the following colloquy ensued: COURT: Okay. What's your proffer? [DEFENSE COUNSEL]: Your Honor, it's the same issue that I dealt with earlier. I think that in order to make an assessment about the effect of contamination in the laboratory, I am entitled to find out how often it happened, if it happened very often with this technician, if it was discussed in the lab, if the lab took steps to deal appropriately with it.       [STATE'S ATTORNEY]: It does not matter if fifty percent of their cases were contaminated. What matters is this one.       COURT: Okay. I thought you were going to ask her, because you had some contamination in one instance, does it carry over to all the rest of them. That's what I thought you were going to ask her. Now, you're going back and rehashing the whole thing over again. I mean, I don't mind you asking her ... if the fact that she had a contamination before, does it carry over to everything they do. [DEFENSE COUNSEL]: [We] also want[ ] to ask her about incidents of contamination in the lab by other technicians. She was allowed to testify about proficiency tests by other technicians.    So she ought to be able to be allowed ... to testify to other incidents of contamination.       [STATE'S ATTORNEY]: Your honor, what is the relevance of other cases? COURT: Yeah, I [STATE'S ATTORNEY]: It's just not relevant.       [DEFENSE COUNSEL]: Your Honor, there's a more general issue here. When a witness says, I've never made an error, certainly I can ... I don't think I'm confined to simply saying well, what proficiency tests have you done. Obviously, I have toI have to be able to cross-examine on the basis COURT: Well, what do you want to ask her about the proficiency test? [DEFENSE COUNSEL]: About how many times these errors have occurred. COURT: To her. [DEFENSE COUNSEL]: About how many times contaminations occurred, yes. COURT: To her. [STATE'S ATTORNEY]: Only to her. COURT: She'sthat's what she answered. She's the one that answered. [STATE'S ATTORNEY]: She can't speak for other technicians anyway. COURT: Yeah.       [DEFENSE COUNSEL]: Your Honor, with all due respect, she already has testified as to the proficiency testing of all the other technicians at Cellmark. So why shouldn't she be able to be asked about contaminations by other COURT: Well, maybe she doesn't know. [DEFENSE COUNSEL]: Maybe she does though. Let us ask the question.       [STATE'S ATTORNEY]: Nobody else touched this case, so what difference does it make? At that point, the trial judge asked Weber whether she knew when other technicians in the lab made mistakes, and Weber responded that she did not. Because the question occurred at the bench conference, the jury did not hear the question or Weber's response. After Weber answered the question, the judge ended the line of inquiry, and defense counsel objected to not being allowed to further pursue the line of questioning. Our review of the trial transcript convinces us that the trial judge erred in restricting defense counsel from cross-examining Weber concerning the frequency of contamination during PCR testing at Cellmark. Williams should have been allowed to pursue fully questions regarding testing errors and possible spill-over contamination in the lab. As a general rule, great latitude should be allowed in the cross-examination of expert witnesses. 3 CHARLES E. TORCIA, WHARTON'S CRIMINAL EVIDENCE § 601, at 160 (13th ed.1973). See also 2 SPENCER A. GARD, JONES ON EVIDENCE § 14:30, at 665-67 (6th ed.1972). Thus, as a general matter, when DNA evidence is admitted against an accused in a criminal trial, questions on cross-examination regarding how that specific DNA evidence was obtained, and the laboratory conditions under which the DNA tests in that case were conducted, should be allowed. See United States v. Bonds, 12 F.3d 540, 563 (6th Cir.1993)(noting that `vigorous cross-examination of the government's experts' assists the jury in determining how much weight to give DNA evidence) (citation omitted); State v. Cauthron, 120 Wash.2d 879, 846 P.2d 502, 512 (1993)(noting that thorough cross-examination of State's experts on the possibility of error in the laboratory and errors in the proficiency test allowed the jury to get a balanced picture of the DNA evidence). Furthermore, cross-examination about incidents of spill-over errors and other contamination was especially pertinent in the instant case given that the test results were obtained using PCR testing. Possible contamination of samples is a major concern with the reliability of forensic use of PCR testing: [T]he extraordinary sensitivity of PCR is known to make it susceptible to contamination and may, therefore, be its Achilles heel. Contamination of the PCR reaction in a forensic laboratory with even the smallest trace amounts of DNA from another individual could produce a misidentification. Although this is likely to be rare, there is no way to demonstrate whether cross-contamination has or has not occurred. Cross-contamination occasionally occurs in molecular biology laboratories, and has been a concern with respect to the use of PCR in medical research. Hence, PCR requires extraordinarily tight quality control assurances. (Footnotes omitted). William C. Thompson and Simon Ford, DNA Typing: Acceptance and Weight of the New Genetic Identification Tests, 75 VA. LAW REV. 45, 77-78 (1989). See also Note, Janet C. Hoeffel, The Dark Side of DNA Profiling: Unreliable Scientific Evidence Meets the Criminal Defendant, 42 STAN. L. REV. 465, 482 (1990)(The PCR technique ... is particularly susceptible to contamination....). A 1992 report on DNA testing produced by a committee of leading forensic scientists stressed the importance of preventing contamination problems in laboratories where PCR testing is performed: One of the most serious concerns regarding PCR-based typing is contamination of evidence samples with other human DNA. PCR is not discriminating as to the source of the DNA it amplifies, and it can be exceedingly sensitive. Potentially, amplification of contaminant DNA could lead to spurious typing results. COMMITTEE ON DNA TECHNOLOGY IN FORENSIC SCIENCE, NATIONAL RESEARCH COUNCIL, DNA TECHNOLOGY IN FORENSIC SCIENCE, at 65 (1992). [7] In the instant case, Williams sought through the proffered line of questioning to cast doubts on the reliability of the testing procedures used by Cellmark. This was a legitimate method of responding to the DNA evidence, especially considering the well-recognized effects of contamination on PCR test results. Cross-examination of Weber regarding the frequency of spill-over errors and contamination in the laboratory could have been vital to the jury's determination of how much weight to give to the PCR test results. See Armstead v. State, 342 Md. 38, 66, 673 A.2d 221, 235 (1996)(noting that case-specific challenges to the manner in which a particular [DNA] test was conducted ordinarily go to the weight of the evidence). Therefore, we hold that the trial judge erred in restricting Williams from fully cross-examining Weber concerning the prevalence of testing errors and contamination during PCR testing at Cellmark.
Williams also contends that the PCR test results themselves should not have been admitted at trial. In Armstead, our most recent case dealing with the admissibility of DNA evidence, we delineated the general principles governing the admissibility of scientific evidence in Maryland courts: [N]ovel scientific evidence may become admissible in one of several ways. First, the evidence may be admitted by statute, if a relevant statute exists. See 5 MCLAIN, MARYLAND EVIDENCE § 401.4(c), at 277-78 (1987). Second, the proponent can prove that the evidence meets the Reed standard of general acceptance in the relevant scientific community. Reed v. State, 283 Md. 374, 381, 391 A.2d 364, 368 (1978)(quoting Frye v. United States, 293 F. 1013, 1014 (D.C.Cir.1923)). 342 Md. at 54, 673 A.2d at 228-29. DNA evidence obtained using RFLP testing is admissible in Maryland pursuant to statute. See Md.Code (1974, 1995 Repl.Vol.), Courts & Judicial Proceedings Art., § 10-915. The statute does not apply to DNA evidence obtained using PCR testing, and this Court has not passed on the question of whether the PCR method meets the Frye-Reed test. Because we reverse Williams's convictions on other grounds, we need not decide whether the PCR method of DNA testing is admissible under the Frye-Reed standard. Further, given the rapidly developing scientific data on the reliability of the PCR method of DNA testing, we believe it might be premature to pass on the question based on the record from the initial Frye-Reed hearing in the instant case, which is more than a year old. Therefore, should the State seek to admit the PCR evidence at Williams's second trial, the trial court should consider conducting a new Frye-Reed hearing on the question of whether PCR testing results are admissible.