📄 Motion: DNA mixture interpretation — Thursday, June 22, 1995
Address:
C:\DEPT103\CRIMINAL\1995\JUN\22\MOTION-DNA-MIXTURE-INTERPRETAT.DOC
TRIAL
▲ Day 101 of 167

Motion: DNA mixture interpretation

Date: Thursday, June 22, 1995 • Utterances: 11
Prosecution and defense argue over whether a 402 foundational hearing is necessary before Dr. Bruce Weir testifies about DNA mixture frequency statistics. Clarke argues no hearing is needed because the defense already waived DNA admissibility challenges, and the method question is one of weight for the jury. Thompson counters that the prosecution has been shifting methodologies (likelihood ratios to frequencies) up until the morning of the hearing, and challenges whether Weir's summing technique follows the accepted NRC method. Judge Ito sides with the defense, ordering the prosecution to present a foundational showing before Weir testifies to the jury.
1 MS. KAHN:

Your Honor, I believe Mr. Clarke is going to address the Court on this issue.

2 THE COURT:

Mr. Clarke.

3 MR. CLARKE:

I think just as prefatory comment, I think what we need to look at is the situation we are in at the moment with regard to this particular type of evidence. In particular, if the Court will recall, with respect to the original witnesses in this case, in particular Dr. Cotton and Mr. Sims from the Department of Justice, it was not either their intention or our intention of providing to the Court, or providing to the Court in this case, frequency numbers about mixtures, and that was argued before the Court and ultimately resolved by this Court with the Court's finding that indeed frequencies as to these mixtures were to be presented. And we have operated accordingly since that time. The Court may recall a little bit about the history of that, and in fact there was a good deal of scrambling, for lack of a better term, with the original witnesses in particular, Dr. Cotton, to be able to obtain frequency numbers to describe these mixtures in some fashion. It was determined in the course of that work, as far as mixtures were concerned, that in fact Dr. Weir would describe mixtures and attach frequencies to them. At the point we are at now, it is our intention to present, through Dr. Weir, frequencies with regard to these mixtures that are the product, or actually the result would be a better word, of summing individual possibilities of genotypes in both two-person mixtures, in other words, assuming that a mixture was from two different individuals, as well as three-person mixtures, assuming that a mixture was the product of three different contributions from three different persons. With respect to that procedure, Dr. Weir is perfectly prepared to describe that to the Court and in fact we think we can do that through Dr. Weir in a fairly very understandable fashion. I think we need to reexamine, however where, we are in terms of this hearing. This hearing involves again, if it is granted by the Court, a determination by this Court apparently as to what method of adding frequencies using the summing technique is appropriate.

And we don't feel--in fact, we feel very strongly that is not subject to a determination by this Court in terms of a 402 foundational hearing because it is apparent that Dr. Weir, and as far as our position is concerned, that his method of determining these mixture frequencies is the most appropriate fashion in terms of the summing technique. And it is apparent the Defense feels that a different technique is in fact the appropriate one. That I think is clearly the type of matter that has to be resolved by the trier of fact, not resolved by the Court in terms of a 402 hearing as to which is the more appropriate method to proceed by, assuming that it is in fact a summing technique which the Court will hear clear evidence that it involves adding up different genotype frequencies. I think that is particularly important when the Court recalls that this Defendant completely waived any admissibility about DNA typing evidence. That we felt, as we broached to the Court many weeks ago at this point, certainly cleared the way for the type of testimony, and in fact not even assigning frequencies to mixtures in this particular hearing, but the Court ruled otherwise. So here we are today, the Defense still has not or still has not at least attempted to reverse their waiver of this evidentiary hearing, this Frye hearing in terms of admissibility that we know applies to population frequency data as well, and in this hearing apparently seeks to convince this Court that our expert's method of adding genotypes is not a correct one. That again I think, as the Court should realize, is clearly a matter of weight for the jury; not a matter of admissibility. In many respects, it is not different to this Defendant during testimony about DNA typing itself--itself, objecting to the fact that a procedure wasn't performed properly; therefore, the Court should have an evidentiary hearing. We know that wasn't done in this case and I feel confident the Court would have quickly denied the Defense any opportunity to contest that matter in terms of a foundational hearing because of the waiver that had already occurred. This is not different with regard to these population frequency data. So again it is our position the Court has no need whatsoever for an evidentiary hearing. If the Court would like an explanation from Dr. Weir about how he summed these different genotype possibilities, that can be done, certainly, and perhaps may satisfy the Court that in fact there is no need for a hearing whatsoever.

But again, it is our position that we are ready to proceed in front of the jury, when the jury is available, with Dr. Weir's testimony about adding genotypes together in terms of these mixture frequencies and we feel that the Court can conduct that hearing--I'm sorry--can allow that testimony to be presented with no hearing necessary whatsoever.

4 THE COURT:

All right. Thank you. Mr. Thompson. A hearing to determine whether we are going to have a hearing.

5 MR. THOMPSON:

All right. Well, I think Mr. Clarke has correctly characterized what the Prosecution is doing is scrambling. At this point it is not entirely clear to us what they intend to present. They early on presented a report--I guess earlier on, in the middle--let me trace the--let me trace the history of what has happened here. We got a report from Dr. Weir in May 11--on May 11th that was presenting likelihood ratios, to characterize these mixtures, and we registered our objections. On May 31st there was another draft report also using likelihood ratios and saying likelihood ratios are essential to characterize mixtures. On June 20th, that is Tuesday, we got yet another report saying likelihood ratios are essential. We were all geared up to challenge likelihood ratios when we learned Tuesday that they were presenting frequencies instead and we got a report on their frequency method. Well, it has been drifting in. We got some of it yesterday morning, some of it was faxed to the hotel last night and corrections were just given to us this morning, so we are just getting this revision that presents what they are calling frequencies. In fact, it appears to me the frequency--what they are calling frequencies are in fact the same numbers that they were calling likelihood ratios earlier, they are just recharacterizing them. Now, as far as whether a 402 hearing is necessary, I think one is necessary to allow you to rule on the foundational objections that we are raising to whatever it is that they are going to present, without which we are still somewhat confused. I think it is clear that the presentation of likelihood ratios is unprecedented. Presentation of frequencies in connection with mixtures or the proper approach to computing frequencies in connection with mixtures is again an issue that has not been--that has not been discussed in the appellate case law and an issue about which there appears to be some scientific controversy. It is our position that if they do present statistics in connection with mixtures, which they are required to do under this Court's ruling and we believe under the laws of this state and particularly under People versus Barney, that they must computer those frequencies according to an accepted method. And we are taking the position that the accepted method is the National Research Council's method which we have discussed with you earlier. I think it is quite clear, from what we've seen from their reports, that they are not computing these mixture statistics according to the National Research Council's method; they are using a different method, and they are using a method to which we have a number of substantive objections that go beyond the general acceptance and following of correct procedures. In particular, we take the position that the way in which they are calculating these frequencies is argumentative, that it incorporates assumptions that are consistent with Prosecution evidence in this case, that it invades the province of the jury by presenting argumentative conclusions in the guise of expert testimony. We also contend that this evidence is objectionable because it fails to take into account all important variables that should affect the conclusions that they purport to be drawing from it and therefore it is objectionable under People versus Chela, a case we cited to you in our notice of objection filed earlier. We will argue that it is extremely prejudicial and therefore excludable under 352 as well. In order to rule on all of these objections, these latter objections having nothing to do with Kelly and having nothing at all to do with the waiver that occurred with respect to DNA evidence, per se, you are going to need to hear some testimony. We are going to need to cross-examine Dr. Weir to find out what exactly it is that he is purporting to present. And then we would like to present expert testimony from Dr. Shields who will tell you that what--what Dr. Weir is doing appears not to be the National Research Council method and that it has problems, which he can explain. So all of these--these factual issues need to be put on the table in order for you to rule on the--on the objections. As far as waiver goes, I mean, when we withdrew our objections to the admissibility of--of DNA evidence in January, no one was contemplating likelihood ratios and the of ever mixture statistics hadn't been raised at that point at all. And certainly the fact that we withdrew our objections to DNA evidence at that point does hot give the Prosecution license to present to the jury any kind of--any kind of scientific testimony they choose, regardless of its scientific validity and regardless of whether it is prejudicial or misleading or argumentative. All of these objections are maintained. Those are trial objections and foundational objections which in your rulings you recognized are preserved. Therefore a 402 hearing is necessary and we would like to proceed with it.

6 THE COURT:

All right. Any brief response, Mr. Clarke?

7 MR. CLARKE:

Yes. Thank you, your Honor. I think the Court has already been made aware that it is not our intent to use likelihood ratios and I think everyone who has been involved in this over the last several days is aware of that fact and in fact the particular summing type of frequencies for these mixtures that is going to be sought to be offered in front of this jury is a summing technique, it is a summing technique that is described by the NRC report. Who while describing it in somewhat vague fashion, clearly in our view covers the exact technique used by Dr. Weir in this particular case. But most importantly, I think Mr. Thompson has brought up the very words that show why this hearing shouldn't be conducted and that is general acceptance. He specifically mentioned an allegation that the method used here is not generally accepted, and those are exactly the terms that were waived or the type of foundational showing that was waived by this Defendant many months ago. These are factual issues, as he just described them, which are the exact same types of issues that are to be decided by juries and not by courts in terms of admissibility. There is at this point, based on the offer or at least the comment by counsel, absolutely no need for a 402 hearing. If the Court would like to ensure that the technique used to be testified to by Dr. Weir involves a summing technique, we would be happy to have him describe that and it wouldn't take very long. But I think in terms of an admissibility hearing, this Defendant again gave up that right many, many months ago.

8 THE COURT:

All right. Thank you, counsel. Counsel, I think that the unfortunate situation we have here is that this is a relatively novel situation. There are no reported cases that deal specifically with mixtures in the forensic setting. Although there is--there are reported cases in the analogous paternity setting where obviously by definition you have mixtures, there is--there does appear to be some controversy in the area that I have read about in my preparation for today's hearing. And the thing that concerns me most is whether or not this is going to be unduly confusing to the jury, so on the bases of both evidence code section 402 and 352, I'm going to require the Prosecution to present to the Court a foundational showing that this should be presented to the jury.

9 MR. CLARKE:

Very well.

10 THE COURT:

All right. So the burden is on the People. Mr. Clarke.

11 MR. CLARKE:

Yes. Dr. Bruce Weir, please.

Temperature

procedural

Key Quotes (4)

Lance A. Ito
A hearing to determine whether we are going to have a hearing.
Ito's dry aside captures the procedural absurdity of the moment — a meta-hearing about whether a hearing is warranted.
Mr. Thompson
We got some of it yesterday morning, some of it was faxed to the hotel last night and corrections were just given to us this morning, so we are just getting this revision that presents what they are calling frequencies.
Illustrates the defense's legitimate grievance — the prosecution's methodology was shifting in real time, making meaningful preparation nearly impossible.
Mr. Thompson
In fact, it appears to me the frequency--what they are calling frequencies are in fact the same numbers that they were calling likelihood ratios earlier, they are just recharacterizing them.
Core defense accusation: the prosecution relabeled the same contested numbers to avoid a challenge to likelihood ratios.
Lance A. Ito
The thing that concerns me most is whether or not this is going to be unduly confusing to the jury, so on the bases of both evidence code section 402 and 352, I'm going to require the Prosecution to present to the Court a foundational showing that this should be presented to the jury.
Ito's ruling against the prosecution — invoking both foundational admissibility (402) and prejudice/confusion (352) as grounds.

Evidence (5)

Informal
Dr. Weir's May 11 report presenting likelihood ratios for DNA mixtures
referenced by Thompson as evidence of prosecution's shifting methodology
Informal
Dr. Weir's May 31 draft report, also using likelihood ratios
referenced
Informal
Dr. Weir's June 20 report, still using likelihood ratios
referenced
Informal
Dr. Weir's revised frequency report, partially received the morning of the hearing
contested — defense argues it repackages likelihood ratios as frequencies
Informal
NRC (National Research Council) report on DNA forensic statistics
cited by both sides — defense argues it mandates a specific accepted method; prosecution claims Weir's summing technique is covered by it

Notable Exchanges (2)

George ClarkeMr. Thompson
Clarke argues the defense waived any right to challenge DNA statistical methodology when it withdrew its Frye hearing objections in January; Thompson counters that no one was contemplating mixture statistics or likelihood ratios at the time of that waiver, so it cannot extend to novel methodologies introduced months later.
strategic
Lance A. ItoGeorge Clarke
After hearing argument, Ito rejects Clarke's position that the court has no role and orders a foundational showing, citing both novelty of the area and jury confusion concerns under 402 and 352.
decisive

Light Moments (2)

Lance A. Ito
After Clarke's lengthy argument about whether a hearing is needed, Ito quips: 'A hearing to determine whether we are going to have a hearing.'
George Clarke
Clarke himself uses the word 'scrambling' to describe the prosecution's efforts to produce mixture frequency numbers from Dr. Cotton — an unusually candid admission of disarray.

Credibility Attacks (1)

⚔ Dr. Bruce Weir
methodology challenge
Thompson argues Weir's summing technique departs from the accepted NRC method, incorporates assumptions consistent with prosecution theory, is argumentative, invades the province of the jury, and fails to account for important variables — anticipating cross-examination and a competing defense expert (Dr. Shields).

Objections

None recorded
Proceeding 6508 • 11 utterances
Criminal Trial
Department 103
⚖️ Start
📂 JUN 22, 1995 📄 Motion: DNA mixture interpreta
JUN 22, 1995 KRT DvH TD