Drug Identification & Chemical Testing for DWI Defense
Student: So there’s enough sugar in the blood to produce up to 0.13?
Kevin Leckerman: Well, it depends on the blood. Everybody’s different. Some people have low blood sugar issues.
Student: But potentially it can go up to 0.13?
Kevin Leckerman: There are a lot of combinations. So, yes, and it depends on how much sugar – there’s going to be enough sugar for these microorganisms to start munching away. It depends on the temperature that the blood is at and how long this microorganism has been able to start contaminating.
Chris: What’s significant about it is it still creates a defense (if you’re on the defense side of the case) because in Jersey there are two tiers – there’s an 0.08 to an 0.99 and an 1.0 and above, and there’s also 0.05 for the purposes of interlock and no interlock – so there are different milestones for sentencing and if you can say, “Once you get above the 0.13 you’re not going to get contamination internally from this fermenting.”
Student: I guess that’s what I was getting at. If there’s only going to be a 0.01 or a 0.02 difference, it’s not going to skew much.
Chris: You don’t know that because everybody’s got a different amount of glucose.
Student: So there’s no way to tell how much?
Chris: That’s what the defense would want to say. You don’t know. All you know is this could be an artificial 0.13 – maybe it was an 0.08, maybe it was a 0.09. We don’t know how much of the metabolic process is associated with what happened in the tube versus what they pulled out of the person’s arm.
Kevin Leckerman: You couldn’t tell – let’s say I was an 0.02 and then the neo-genesis occurred on top of that and it brought it up to a 0.11. The lab can’t tell me how much ethanol was produced through contamination or what my BAC was without the contamination. You can’t tell because you can’t separate it. It’s all ethanol.
Kevin Leckerman: Hemolysis – that’s the breakage of the red blood cells and that’s going to release hemoglobin and other proteins into the blood. For your purposes, what it does it is creates more fluid which will increase the amount of ethanol that’s going to be detected through testing.
Hemolysis can be caused by a number of different things: improper venipuncture site, prolonged tourniquet time (if they’re leaving the rubber tourniquet on for too long). If the needle’s drawn too slowly or too fast, those are problems with hemolysis. As I mentioned before, there’s a proper way of inverting the tubes. If the nurse is shaking the tube, that’s going to cause hemolysis. It’s going to interfere with the test method, skew the results, and clotted blood will cause an overestimation of BAC.
Kevin Leckerman: Let’s talk about testing. The scientific term is “assay.” There are different types of assays. I’ve only listed a few of them and we’re going to talk about three specifically.
Aside from amino acid testing we’re talking about chromatography. Gas chromatography is what we’re going to be addressing today, and with gas chromatography there are different detection methods. So I’m going to explain to you how the gas chromatograph is attached to the detector, and different detectors can be used for finding different things. There are different detectors that you should use for different analytes – specific compounds that you’re looking for. With alcohol, flame ionization detectors are what you use. Headspace gas chromatography with flame ionization detection is what you do. That’s the best way the labs use to not only identify but quantitate alcohol. With drugs: gas chromatography, mass spectrometry, and then you have all these other types – [combustion detector, compactivity detector 00:39:03]. There’s liquid chromatography, so instead of a carrier gas going through the machine, it’s actually a liquid pushing the compounds through the machine. That’s not often used and I haven’t seen it used in New Jersey yet, at least for the basic DWI case.
Let’s start with blood testing: serum versus whole blood testing. So as I mentioned before there’s whole blood – the red blood cells, the white blood cells – and what happens is the labs can create a serum, which is separating all the protein, the mass, from the liquid and creating a serum that gets tested. I’m not going to go into too much depth about the serum testing. I’m going to explain what it is, but the reason I’m not going into depth is because, like I said, in New Jersey, it’s not really used. It’s not a forensically accepted practice. Serum testing or amino acid testing is what’s called a presumptive test. There is presumptive versus confirmatory.
Presumptive is essentially screening. The state lab will use the presumptive test to screen the sample and see if it’s really worth their time and money to do the more reliable confirmatory test. So they do the presumptive screening test and then they move on to the better test, essentially.
When have the serum test – this amino acid test – that’s really done at a hospital, so people refer to it as “hospital blood,” as well. The hospitals will do it not for forensic purposes, but for clinical purposes, for diagnostic purposes – for treatment. So they’re not too concerned with how precise they are with the actual result. They just want to find out if there is alcohol in the system and if it’s enough that the person is actually intoxicated, which will affect our opinion and how we treat the person and the diagnosis that we give. That’s what they use it for. They’re not thinking that this is eventually going to be used later on for a DWI prosecution.
So, why does it come into a DWI case? Well, there could be a situation – let’s say there’s an accident – and the officer is late to the scene, they take the person to the hospital. There’s no real inkling of DWI at that point, but maybe they get a call from an EMT. It wouldn’t be from the hospital, presumably, but somebody tips him off or maybe there’s a further investigation. It’s a little too late because they arrived at the hospital four or five hours later – too late to get a blood draw and get a reliable result, but they want to get at least some information from the hospital lab. So they get a subpoena, they get that information, and then they try to use that in their case. What are the problems with that, aside from the fact it’s not a forensic test but it’s really a clinical test?
Well, I mentioned the presumptive aspect. I’m going to give you a good example. My wife and my daughter got sick at the same time, both with an intestinal bug. The insurance companies – for adults – don’t want to do confirmatory tests. So if any one of us gets an intestinal bug, we’re kind of out of luck in a way because the insurance company is not going to pay for the more reliable test; they’re going to want the lab to do the presumptive test. What’s the problem with that? Well, the problem is it has high false negative rates and high false positive rates. These tests could be as reliable as only 75%. Twenty-five percent of the samples that get tested may come back negative when they’re actually positive.
So the example of the problems with the presumptive test: my daughter’s four and she gets her test at children’s hospital in Philadelphia where they use confirmatory tests. The lab there is specifically set up; labs have to be set up for specific testing processes. You can’t just say, “Hey, lab, test this and do the more reliable test.” It doesn’t work that way. So for kids, I’m just assuming: you have to make sure the insurance is going to pay for this, you have to make sure to diagnosis it correctly before a child gets really sick, things like that.
So my daughter gets tested and the test comes back positive; she has this bug, takes the medication, and it goes away in a couple of days. My wife gets tested; she feels awful but the tests come back negative. She proceeds to feel awful over the course of two months. She gets tested over those two months five separate times. Four tests come back negative; the fifth test comes back positive. They give her the medication and she feels good three days later. So that’s the problem with the presumptive test.
Serum Blood Analysis
Kevin Leckerman: Like I said, it’s done the in the hospital. What typically happens is when you separate the whole blood and just test the serum, it actually creates a higher level of ethanol. Is there a known correlation between whole blood and serum blood once it’s been tested? If it was tested with a whole blood confirmatory process, what would be the correlation? There’s supposedly a 0.16 correlation. You multiply the final result by serum by 0.16, and it’s going to reduce the final serum result and you’re supposed to get the whole blood result. It doesn’t work that way, though. If you ask true scientists, there are studies out there that say that there’s a 0.16 correlation. However, it doesn’t necessarily work that way. Most scientists will tell you that there is no reliable study out there to show that there’s a correlation.
To go quickly through this: serum blood analysis involves acid that’s added to the whole blood sample, which essentially deproteinizes the sample. It’s homogenized, meaning the sample is mixed up, and then placed into a centrifuge to actually separate, so you get either plasma or serum for analysis.
That’s a centrifuge. You just put the vial on it and it just whips it around, and eventually that causes separation.
Chris: The reason he’s doing this is because the indirect analysis he’s
referencing is – usually it’s hospitals – it’s attractive to them because they can do it and get an analysis quickly and see what’s [inaudible 00:46:30] for the purposes of medical treatment. It’s not necessarily as forensically reliable as you want, but the reason you run the centrifuge is you want to get the red blood cells to the bottom as a precipitant. You now have a more clear serum or plasma because you’re going to end up using photometric analysis; you’re going to be shining light and you want to have the clearest sample you can once you induce a chemical reaction to start the process.
Kevin Leckerman: And this process is faster, so you may be thinking, “Why do they use this process instead of the more reliable one?” It’s just faster and cheaper. You can do it on an individual basis as opposed to laboratories where they try to get as many samples as possible and do it all at once in what’s called a run. So this is easier.
The difference between the presumptive and the confirmatory testing is that they’re not testing the alcohol. What they’re doing is they’re testing out the alcohol metabolic process. They’re making ethanol into acetaldehyde, they’re adding ADH (which is a chemical) and NAD, and then they’re forming NADH. They’re testing the amount of NADH. So you’ve got this ethanol in your system and you put all these chemicals in there, and there’s supposed to be a correlation between the amount of NADH and ethanol when they measure the NADH; they’re not even measuring actual ethanol. And as Chris mentioned, they use light testing to determine how much NADH there is.
Chris: If some of those letters look familiar to you, remember when Doctor Saperstein was here we were talking about the metabolic process with alcohol and what happens in your liver when you actually metabolize it. All those things are in your body. The alcohol dehydrogenase – you have that; that’s indigenous to your liver. You metabolize that, so you’re trying to recreate this essentially in a test tube of serum blood. The problem is they’re only looking for the net result that spins off of it, and not the actual ethanol content.
Kevin Leckerman: Another issue that comes is somebody being treated with lactated ringers. That’s going to affect the serum blood result. The other thing is, hospital labs are clinical labs. They have proficiency testing to see how good they are at coming up with the results. They have a plus or minus 25% for the mean, so they can be as off as 25% high or low on these results and that’s okay for the proficiency testing. That’s the difference between forensic labs and clinical labs: forensic labs are supposed to have a tighter proficiency.
Here are some other issues I’m not going to go into; we’re running out of time. What you need to know in New Jersey is there’s a case, State v. Lutz, 309 Super. NJ 317 – bad case, which basically allowed this hospital result to come in with this 0.16 correlation. If you know the science and you look at it, you know it either wasn’t explained to the judge correctly why this shouldn’t be accepted, or simply the court just didn’t seem to understand the science behind it. It’s good case law, but it can be overturned if you get the right experts in it and if you know enough about it.