📄 DNA mixture discussion — Tuesday, May 9, 1995
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TRIAL
▲ Day 70 of 167

DNA mixture discussion

Date: Tuesday, May 9, 1995 • Utterances: 33
Before the jury was brought in, Prosecutor Rockne Harmon argued at length that the People should be allowed to present DNA mixture results without statistical frequencies — reporting only a 'failure to exclude' rather than a numeric probability. Defense attorney Peter Neufeld countered that People v. Barney and the NRC report both require statistics to accompany any DNA inclusion, and that omitting them on mixed stains (some excluding as little as 62% of the population) would mislead the jury. Judge Ito reserved ruling, saying he'd read the cited case law overnight since the mixture results wouldn't be reached that afternoon.
1 (The following proceedings were held in open Court, out of the presence of the jury:)
2 THE COURT:

Back on the record in the Simpson matter. All parties are again present. The jury is not present. Mr. Clarke, you indicated there was a matter that we should take up before we proceed with Dr. Cotton.

3 MR. CLARKE:

I'm sorry, your Honor, were we going to proceed on the two items, that is, the instruction as well as the mixture?

4 THE COURT:

I'm more interested in the mixture aspect.

5 MR. CLARKE:

Okay. With the Court's permission, Mr. Harmon has been preparing a response to that. The Court may recall I had to do it on fairly short order last Friday, and with the Court's permission, I would like him to address this issue.

6 THE COURT:

All right. Good afternoon, Mr. Harmon.

7 MR. HARMON:

Good afternoon, your Honor. Perhaps the best starting point, that in terms of the mixture results that we have obtained on numerous items in this case, we have never intimated that any of those items match anything. And I know that the Court has been concerned about language from legal opinions talking about evidence of a match without a statistic is meaningless. These are not matches; these are results which are consistent with or in another context that the sources have not been excluded by the testing that was done. One could imagine a scenario where you have two rapists and only one of them is identified and a victim identifies that person and both assailants have raped the victim and both have ejaculated and DNA typing of either is done and it is clear that there is a mixture or a combination, more than one sperm donor, and we only have one Defendant at the end of the table and his type is consistent with the mixture that was obtained there.

It is the People's position in this case, even though that that is not directly on point, that that sort of evidence could be presented and explained to the jury what it means and what it doesn't mean, without assigning any statistic to it. The Court was interested in any legal precedent on the issue. I don't think there is any legal precedent that says that we have to do what the Defense wants us to do in this case, and I think that is the appropriate question to ask, what is the legal precedent that forces us to do what they have sought or what they are seeking in this case? There is legal precedent in the conventional serology area that points out that we don't have to do what they have asked us to do, and not coincidentally, one of those cases is a capital case that I tried, I was the Prosecutor in, People versus Wash, 6 cal.4th 215. I can speak from personal experience and also relate what is in the opinion, because this is what happened in every sexual assault case where conventional serology was done.

8 THE COURT:

Mrs. Robertson, 6 cal.3d, please.

9 MR. HARMON:

Where conventional serology was performed, and we haven't heard much about an aspect of DNA typing that dramatically changed forensic analysis, that is in DNA typing it is possible to separate the male DNA from the female DNA in sexual assault cases and that is why in sexual assault cases DNA typing of any form is a very powerful tool. Before DNA typing came along it was impossible to separate out the male biological material from the female biological material. And in each and every sexual assault case the evidence was presented as a failure to exclude, and People versus Wash stands for that proposition. What People versus Wash does not stand for is the proposition that the Defense is arguing in this case that has never been applied in conventional serology, that in those sexual assault cases, in order to present any of our results of a failure to exclude, we would have to sum up all of the possible combinations of the biological markers of both the male and the female. And so I point that out because there is a total amount absence of any legal issue on that point. We were never compelled to do that. We didn't do it in wash. It was not done in another California Supreme Court case dealing with sexual assault evidence, People versus Ashmus. It is impossible to separate out biological markers.

10 THE COURT:

How do you spell that?

11 MR. HARMON:

A-S-H-M-U-S. The cite is 54 cal.3d 932. So I just point that out because they don't say we don't have to do that, but they do stand for the proposition that the same arguments could have been applied and were not applied in that situation. I think it is important to look at where this issue first came or became injected into this case. I'm not sure who wrote this brief, but it is replete with references to Professor Thompson where he wrote his own brief and then cites things that he has published on this article or in the article. If you recall--and this began on page 21 and it spanned several pages, if you recall, the argument was first broached in an admissibility context. The evidence would not be admissible unless. And if you recall, the initial argument was that what I would not--we should not be allowed to report, if we had a mixture that clearly came from more than one person, that we should not be allowed to say, aha, we see one of these people in there and the frequency for that one person is ten percent. And that was never our intention. Our board does not have frequencies. That--and so the argument--

12 THE COURT:

There is no frequencies as to mixtures.

13 MR. HARMON:

As to mixtures. As to mixtures.

14 THE COURT:

All right.

15 MR. HARMON:

Then--

16 THE COURT:

You are only seeking to report that as a failure to exclude?

17 MR. HARMON:

We are seeking to report the data, and I will get to that in a minute, why that is important, and if there are innocent explanations for this, we would love to hear what they are, but I will discuss the data in just a second. Mr. Or Professor Thompson's brief then goes on to claim that there is nothing about the forensic context, there is nothing about the observations in these tests that can allow a scientist to assign relative proportions or to sort out what is clearly a mixture. And that is all well and good. That is what Professor Thompson says, but he is not a Professor in forensic science. The Defense's own primary PCR consultant, the fellow whose name I keep mentioning, Dr. Blake, has published extensively on interpreting mixtures by relative intensity. And I think it is important to keep that in mind. I doubt we will be seeing him in this case, so this is the most that we can hear from him, but let's--an article, I think it is the case work article in the journal of forensic science by Edward Blake, Jennifer Mihalovich, M-I-H-A-L-O-V-I-C-H, Russ Higuchi, Sean Walsh and Henry Erlich at page 706. Dr. Blake and his colleagues say: "the detection of mixtures depends in part on the fact that any one individual can have at most two alleles of a given gene. The presence of more than two alleles in a sample indicates a mixture. Even if only two alleles are present, a mixture can still be detected if the two samples are mixed in different proportions. In this case, a mixture is suspected if the relative dot intensities corresponding to the two alleles are different."

And then he goes on to describe other things that appear in sexual assault cases. Later on at page 722 in the same article Dr. Blake again discusses mixed genotypes. "another issue that has arisen in some cases is the ability to analyze mixed genotypes in biological evidence," and then the passage discusses how you can do that. Probably the most instructive article by Dr. Blake, it is a chapter in a book--chapter 17--unfortunately I don't have the title of this book--it is called "applications of PCR to the analysis of biological evidence." It is by Cecilia von Beroldingen, and that is b-e-r-o-l-d-I-n-g-e-n, and Edward Blake, Russ Higuchi, George Sensabaugh and Henry Erlich. And in that chapter Dr. Blake has a very interesting case work example, and I will just paraphrase it. It is a sexual assault case where the victim had had consensual sex with her husband, I think nine hours prior. And when the evidence was analyzed, a sample--you always try to obtain a sample from the last consensual sex partner in a sexual assault case just to make sure that what you are getting is what you think you are getting. And in this case Dr. Blake not only sorted out by relative intensity and found a much bolder pattern for the person who was accused of the crime, but he said, well, there is a fainter pattern there and that is consistent with the husband. And then Dr. Blake, in this mixture, did something that we don't seek to do in this case, he calculated the frequency for the bolder pattern, because that was the assailant in the case. Why sum up when you know where the other stuff came from, the DNA pattern from the victim's husband? So while it is easy for whoever wrote that brief to say you can't do that, there is neither the law on their side to say that we can't do--all we are doing is we say here is a mixture, here are the alleles that we saw, here is the data that we saw with no frequencies. Now, it is--for example, there are two series, I think, and specifically with respect to the Department of Justice results, there are three stains on the center console of the Bronco. They show a clear mixture. There is more than two alleles. And what is clear is that the mixture could not be from Mr. Simpson alone because there is more than one person clearly there. What is also clear is the mixture just happens to contain alleles from the two victims in this case. We turn the table a little bit when it comes to the glove, and I'm just talking about the PCR context of this glove. On the glove, by both RFLP and PCR we've got--there are discreet stains that type very powerfully to Mr. Goldman and nobody else. Very powerfully. The frequencies or the estimates in that are in the millions. There are others which are combinations of both Nicole and Ronald and those were typed by both PCR and RFLP and there are relative intensity differences in both the RFLP and PCR results in those cases. And that is all part of the forensic picture on this case. So when it comes to several stains that are right around the notch area where we see these consistencies, we see something that is inconsistent with the two victims in this case that we have proven very powerfully are there, and among the three people that were involved in this case, it is only consistent with Mr. Simpson. And that is all the jury--that we want to tell the jury. To preclude us or to try to present some sort of estimate about--that calculates a meaningless expression, there is simply no legal basis for it and it is totally contrary to the Defense's leading expert on this area whom we will probably never see in this courtroom, Dr. Blake. I think finally, we've gotten the cart before the horse in this case. We have boards. They have launched an objection. I think they are the moving party in that instance, your Honor, and all they have said is you have to do something. I have demonstrated and I will be glad to provide copies of those articles, that there is a scientific basis for us to do what we want to do. They have not demonstrated that there is no scientific basis. I think it would be appropriate at this point--they have never suggested what those frequencies should be in this, and I can tell you, having dealt with statisticians, that you can define a different question that will change the number. I would suggest, and all we are asking to do is we want to present our results to people who are anxious to hear the results of this typing. The Defense does--and there are no statistics on those boards. It has always been our intention with mixtures not to present statistics, but to explain the results fairly, equivocally and unambiguously and let the jury decide what they mean. The Defense, on the other hand, wants to force us--this is the narrow legal issue that has allowed me to speak for fifteen minutes--the Defense wants to force us to put a meaningless number up there that they can either elicit on cross-examination--we know they can't call Dr. Blake on this point--but to call somebody else to do that.

And I think it is time to move on with the trial and deny their objection to this, or the alternative is to force them to sustain their burden of proof that there is both a legal and a technical objection to it and at that point we will be happy to point out, in or out of the presence of the jury, why we should be entitled to present the results in the form that we would like to present them.

18 THE COURT:

Mr. Harmon, when do the People anticipate getting to actually presenting these results?

19 MR. HARMON:

Could Mr. Clarke address that, because he is up now?

20 MR. CLARKE:

As far as the results board themselves--

21 THE COURT:

And specifically the mixtures.

22 MR. CLARKE:

--I will anticipate that we will start the viewing of autoradiographs but not get as far as the results that are at issue, the mixtures.

23 THE COURT:

This afternoon?

24 MR. CLARKE:

Correct.

25 THE COURT:

All right. Mr. Neufeld.

26 MR. NEUFELD:

Thank you, your Honor. Well, I think what you do have here, your Honor, is an attempt, at least by Mr. Harmon, to selectively present statistics to this jury. And frankly, in the words of Marcia Clark, what is really going on here I think is an effort on their part to mislead, distort and confuse the jury by doing so. And in response to Mr. Harmon's suggestion that there is no legal authority to the contrary, there is. People versus Barney, in the first department they said explicitly that if you want to present DNA evidence you do so with statistics, otherwise it has no evidentiary value. And your Honor adopted that same ruling in the Court's opinion on the DNA objections on April 7 of 1995. Dr. Blake, by the way, who Mr. Harmon refers to, routinely in trial case after trial case aggregates in mixtures the various genotypes and always gives a sum. That has been his standard practice. We have seen him do it in more than a dozen cases and that is the procedure in fact used by serologists and geneticists all over the country, as far as we know. It is also the policy and practice adopted unequivocally in the national academy of science inquiry into the proper usage of DNA testing.

27 THE COURT:

Do you want to cite me to the page?

28 MR. NEUFELD:

Yes, I will give you the page. One second.

29 (Brief pause.)
30 MR. NEUFELD:

Umm, on page 59 it says, and I quote: "if a suspect's pattern is found within the mix pattern, the appropriate frequency to assign such a `match,'" unquote, "is the sum of the frequencies of all genotypes that are contained within that mix pattern." Okay. So that is what they are saying. I have never seen any scientific authority any place to the contrary. It is the standard practice used by professional serologists and geneticists, when testifying to the results of a mixed stain, that I am aware of. I would also point out, your Honor, and I don't--I don't want to spend much time on it, but you may recall when we brought up this issue last week with you, you said if they had any legal authority to the contrary that it should be given to the Court last Friday and given to counsel last Friday. I asked again whether there was any authority yesterday and I was told there was none and all of a sudden Mr. Harmon comes in here to present his argument and for the first time we are hearing references to legal authority. And I don't believe that this is consistent with the instructions that you have given, not only in this particular issue, but all issues that have come before your Honor during the pendency of this case. I don't even know, because I haven't seen those cases yet, whether or not this specific objection is even raised. Did the trial lawyers say that it was error to admit the evidence in the absence of statistics and was that issue precisely addressed on appeal and resolved by the appellate Court? I don't even know if the cases even stand for the proposition that Mr. Harmon is suggesting, but you do have legal authority here and the legal authority is Barney. And in the conventional serology cases, your Honor, are not terribly useful on this point because Barney was decided in the context of the power of DNA evidence, certain cache that comes with saying you have a DNA match. And we all know that outside this courtroom that we are talking about things like uniqueness or an extremely rare possibility. We are not talking about items such as 1 in 20 or frequencies of 1 in 40 in conventional serology.

We are talking about much, much rarer instances here, and it was because of that that the Court in Barney decided that unless you say what that match is or what that inclusion is--and by the way, whether you call it a match, or in a mixed stain context an inclusive, you are basically saying the same thing. In fact, Robin Cotton earlier today was asked to address exclusions and inclusions and was very clear from what she said that when you are talking about inclusions you are talking about that so-called match. And I think you even ruled in the past that they are free to use those words interchangeably when describing the--the concurrence of data in a particular DNA profile. And so what we are saying is and what the Court basically ruled in Barney is it is a foundation issue. It is a foundation issue. You cannot present evidence of an inclusion or a match, whether it is an in a mixed stain or any other type of stain, unless along with it you give the jury some--some generally accepted view of the statistics of that. Now, you have already ruled that they are allowed to give estimates based on the product rule and they are not required to use some other approach, but at least they should be required to use that same product rule that they used for getting frequencies on these single-source stains to the mixed stains. And there is a very straightforward way to do that. It is the way that is described in the NRC report. It is the way that any experienced scientist would do it. You simply look at the different frequencies, they could be the frequencies that some authority has for those different genotypes, and you aggregate them. It is as simple as that, otherwise you really do mislead the jury. I gave you an example the other day of one mixture that they would present through cellmark diagnostics and that is a mixture on the steering wheel in the Bronco. If you have these--these--these other types of evidence where you are saying there is an inclusion and it includes Mr. Simpson or it includes someone else, and you then have a number for that match and you give it a number of one in a million or one in a billion or whatever and then in the very next item you say we have this mixed stain and it also includes Mr. Simpson, but we don't give a frequency for that, then under 352 the likelihood of confusing the jury and leading them to infer that that match has the same power as the match just above it is extraordinary. And in the example I gave, your Honor, the percentage of the population which would not be excluded by that mixed stain profile on the steering wheel is about 38 percent of the population. Now, that is a far cry, just on a gut level, from the kind of power that we ordinarily attribute to DNA testing and that is why Barney says you have to give a statistic. That is why the NRC stays you have to give a statistic. And frankly, I believe that is why you said it in your decision last month and I am simply asking that the same thing be accorded to the People at this time.

31 THE COURT:

All right. Thank you, counsel. All right. Mr. Harmon, I haven't had the opportunity to read the case law that you have cited to the Court. I will read that. And since we are not going to get to those results this afternoon, I will have the evening to think about.

32 MR. HARMON:

Okay.

33 THE COURT:

All right. Let's proceed with the jury.

Temperature

tense

Key Quotes (5)

Rockne Harmon
These are not matches; these are results which are consistent with or in another context that the sources have not been excluded by the testing that was done.
Harmon's core framing — distinguishing 'mixture consistent with' from a positive match, to justify presenting results without frequency statistics.
Rockne Harmon
On the glove, by both RFLP and PCR we've got--there are discreet stains that type very powerfully to Mr. Goldman and nobody else. Very powerfully. The frequencies or the estimates in that are in the millions.
Harmon previews the strength of the Goldman glove evidence while making the broader argument about mixture presentation.
Rockne Harmon
The Defense wants to force us to put a meaningless number up there that they can either elicit on cross-examination... but to call somebody else to do that.
Reveals the prosecution's strategic concern — that defense wants a statistic specifically to attack it.
Peter Neufeld
if a suspect's pattern is found within the mix pattern, the appropriate frequency to assign such a 'match,' is the sum of the frequencies of all genotypes that are contained within that mix pattern.
Neufeld quotes the NRC report page 59 directly, establishing the scientific standard requiring frequency aggregation for mixtures.
Peter Neufeld
the percentage of the population which would not be excluded by that mixed stain profile on the steering wheel is about 38 percent of the population. Now, that is a far cry, just on a gut level, from the kind of power that we ordinarily attribute to DNA testing.
Neufeld's most effective argument — a 38% non-exclusion rate presented without a statistic would falsely carry the weight of typical DNA evidence in jurors' minds.

Evidence (4)

Informal
DNA mixture results from three stains on the center console of the Bronco — showing more than two alleles, consistent with both victims
discussed
Informal
Glove — PCR and RFLP results showing discrete stains typing powerfully to Goldman, plus mixed stains consistent with both Nicole and Ronald, with residue consistent only with Simpson
discussed
Informal
DNA mixture results from steering wheel of the Bronco — Neufeld argues 38% of population would not be excluded
discussed
Informal
Results boards (autoradiographs) — prosecution's planned visual presentation of DNA typing results with no frequencies for mixtures
discussed

Notable Exchanges (2)

Rockne HarmonLance A. Ito
Harmon delivered an extended 15-minute argument citing People v. Wash, People v. Ashmus, and Dr. Blake's own published research to justify presenting mixtures without statistics. Ito peppered him with clarifying questions, including confirming that the prosecution's boards contain no frequencies for mixtures at all.
strategic
Peter NeufeldLance A. Ito
Neufeld rebutted by citing People v. Barney and the NRC report, and complained that Harmon had introduced new case citations after Ito had ordered both sides to submit authority by Friday — arguing procedural bad faith.
heated

Credibility Attacks (1)

⚔ Professor Thompson
qualification challenge
Harmon dismissed Thompson's brief on mixture interpretation by noting he 'is not a Professor in forensic science,' then turned Thompson's own cited authority (Dr. Blake) against the defense by showing Blake's published work supports interpreting mixtures by relative intensity.

Objections

None recorded
Proceeding 5978 • 33 utterances
Criminal Trial
Department 103
⚖️ Start
📂 MAY 9, 1995 📄 DNA mixture discussion
MAY 9, 1995 KRT DvH TD