Field Test Kits That Produce False Positives.

As the name implies, colorimetric field tests indicate the presence of a drug by causing a liquid reagent to change color. The result is called presumptive because, while a color change indicates a possibility that a drug is present, it does not conclusively identify the presence of a controlled substance. The result of the test can only be presumptive because these tests lack the specificity that would be required to definitively identify the substance being tested. In other words, this means that different compounds can trigger identical reactions in the same reagent; in the case of the colorimetric test, that means that different compounds can trigger identical color changes. This fact has been highlighted by a Washington state law enforcement officer during a media interview, including his explanation of “false positives” and demonstrations of colorimetric testing on everyday products. Examples of these “false positives” include the following, among others:

• Hershey’s Chocolate: When the officer performed the colorimetric test on Hershey’s chocolate and flour, it produced a “positive” result for marijuana
• Tylenol PM: When the officer performed the test on a liquid-dosage Tylenol PM, it produced a “positive” result for cocaine

The problem with these tests is that they simply lack the specificity to identify the compound tested, and the test results are mistaken for confirmation of a controlled substance. Ultimately, we believe that this means that, while presumptive results may provide enough suspicion to justify further testing in a laboratory, they do not provide reasonable probable cause to support arrest, a guilty plea, or conviction without subsequent laboratory confirmation.

Why can the Same Reagent Change Color for Legal Material?

One of the main issues with these tests is that the quantity of sample material is often uncontrolled. While laboratory technicians can control the amount of material they subject to a reagent, field testing officers have much more leeway. As a result, excess sample material can overwhelm the reagent and distort the resulting color, leading to a false-positive result.

Even if this is not an issue, legal substances can still produce the same reactions that drugs produce. If you think of a reagent as a test to identify a certain compound, then the test will show a positive result even if that compound is found in an ordinary legal substance. If that legal substance is the same compound that the test is designed to identify, then it will (correctly) produce a positive result, even if the legality of the compound changes based on its source.

While these are the most common causes of false positives in the field, they are far from the only ones. Exposure to air has been shown to cause false positives for some kits, as has exposure to extreme temperatures. Finally, unlike laboratory tests, which are performed under strictly controlled conditions by professional chemists, these presumptive tests are subjected to human interpretation. Testing officers may only have seconds or minutes to identify a change in the reagent’s color and, as a result, the identifications they record can be subjective at best.

At Spodek Law Group, we believe that this risk of error is simply too great for the presumptive results of field tests to support arrest, a guilty plea, or conviction.

While, of course, these presumptive results may provide enough suspicion to justify the seizure of additional evidence for further testing in a laboratory setting, they simply do not provide reasonable probable cause in their own right.

Can Police Treat a Presumptive Result as Proof Before Confirmation?

The role of the prosecutor in a criminal case is to ensure that any conviction is based on reliable evidence. However, when nearly 90 percent of surveyed prosecutors allow guilty pleas to be entered based solely on the presumptive results of field tests, without subsequent laboratory confirmation, it puts the presumption of innocence under threat. The reliance on presumptive field results is further exacerbated when crime labs get involved. In the cited survey, one-quarter (24 percent) of laboratories reported receiving no samples from police in cases when field results already existed. In other cases, confirmation testing was aborted because the defendant had already entered a guilty plea. Nearly half of laboratories surveyed (46 percent) report that they do not perform confirmations after guilty pleas are entered. While arrest warrant applications and bail hearings take place shortly after an arrest, defendants’ counsel have limited time to contest the probable cause involved. In some cases, this limits the time the defense has to properly challenge the presence of any evidence. When field tests are accepted as proof, they may influence bail decisions prior to laboratory confirmation, meaning defendants may unnecessarily face financial or personal hardships based on unverified evidence. Plea bargaining typically occurs between the time charges are filed and when a guilty verdict is reached at trial. During plea bargaining, evidence that is presumptive should not be taken as proof of a criminal violation. However, prosecutors can use field-test results to threaten a defendant with the potential for a high-level sentence, leading to a guilty plea. Defendants’ attorneys do not have time to wait for crime laboratories to analyze field-tested evidence, forcing them to make decisions in a timeframe that often does not allow for an accurate determination. All of this comes together to make our point that the results of field tests should not provide sufficient probable cause to support arrest, a guilty plea, or conviction on their own, but instead only provide enough suspicion to justify the seizure of a substance for further laboratory confirmation.

What Does Laboratory Confirmation Establish That a Field Kit Cannot?

Confirmation tests at a laboratory are used in criminal law enforcement cases to supplement presumptive field-test evidence, by identifying the exact compound (if possible) within the seized material. Confirmatory analysis is different from a presumptive test in that it involves instrumental methods rather than a color-changing reagent, and the results provided are more specific.

Another type of analysis that is used in a crime laboratory is a qualitative analysis, which is the identification of a substance as particular compound in order to determine the compound’s category and legality without making the additional step of measuring its amount. However, if measuring the amount or measuring the sample’s purity is necessary, labs will conduct quantitative analysis.

Gas chromatography is an instrumental method that identifies unknown substances in many types of cases. It works by separating the components within a submitted substance sample and then analyzing the substance sample’s components.

While laboratory testing is a far more comprehensive approach to identification than field testing is, it is not always possible to identify a substance. If a seized sample is too small, then it will be impossible to identify the sample with absolute certainty. Similarly, if the sample is damaged, then the analysis will likely be inconclusive. Spodek Law Group is a law firm handling federal drug cases involving a wide range of substances. If you or a loved one is facing a federal drug charge, get the advice of a team of highly experienced lawyers as soon as possible.

We understand that this is a difficult time for you. While the consequences of a drug conviction can be severe, there are also many defenses that can potentially get the charges against you dropped or reduced. Contact Spodek Law Group today to schedule a confidential case review.

How Have Courts and Reform Reports Responded to Unreliable Color Tests?

The Quattrone Center report highlights several potential reforms that could reduce the impact of errors caused by color-based field tests. These potential reforms include:

• Blind Audits: The report also recommends “conducting regular blind audits of cases using field drug tests to establish error rates” This would make it possible to determine the true error rate of these tests under normal circumstances.
• Presumptive Confirmation: The report also recommends that courts require confirmatory testing “Require confirmatory testing whenever a guilty plea is accepted, with the right to withdraw the guilty plea following a no-controlled substance finding.”
• Rescinding Plea Deals: Following up on this, the report further recommends allowing defendants to withdraw their guilty pleas if “Require confirmatory testing whenever a guilty plea is accepted, with the right to withdraw the guilty plea following a no-controlled substance finding.”
• Cite-and-Release: The report also suggests that police officers “Should field test kits continue to be used in simple drug possession cases, adopt a cite-and-release policy to avoid the coercive effect of detention and its impact on wrongful convictions.”

Over the years, courts have also issued several rulings that have identified errors caused by presumptive field tests. According to one study, at least 131 drug convictions had been overturned, with a majority of these convictions coming from “inaccurate presumptive testing.” When laboratories re-tested samples from these reversed convictions, in the majority of cases, the laboratory result showed no controlled substance. However, some reversals resulted from laboratories finding legal substances. For example, when the sample from a case in Kentucky had been re-tested, the laboratory determined that it contained no controlled substance. The case has been highlighted because the defendant had already entered a guilty plea, and the court accepted this plea based on the presumptive positive result from a field test. The reversal is a prime example of why presumptive results, even if they indicate a positive identification of a controlled substance, should not be used to justify the acceptance of guilty pleas.

Speak With a Federal Defense Lawyer

If you are dealing with any part of what this article describes, the next step is a conversation with a lawyer who handles these cases. Spodek Law Group is a second generation criminal defense firm practicing since 1976, representing clients nationwide from offices in New York, Brooklyn, Queens and Los Angeles. Call 888 348 8028 to speak with our team.