Why it is not legitimate to retrograde extrapolate a DUID result based upon one measurement

Why it is not legitimate to retrograde extrapolate a DUID result based upon one measurement In my lecture yesterday at the OACDL annual OVI conference, I had the task of presenting on “What you need to know about blood.” I had 33 minutes to do so. What can you teach people in 33 minutes on […]

The scariest words in criminal court: “Based upon my training, knowledge and experience”

Seven little words have likely cause more convictions than anything else in all of criminal law combined: “Based upon my training, knowledge and experience.” Every day, in thousands of courtrooms all across the Untied States this phrase is uttered. It has come to be the sine qua non in all criminal prosecutions. Many times it […]

How does a GC-MS machine know that there’s a drug in the blood or urine?

How does a GC-MS machine know that there’s a drug in the blood? The analyst has to teach it. Just like you teach a kid his or her colors, you have to teach this machine what are the drugs it should be looking for. How were you taught what color is what? You probably don’t […]

The top 2 problems seen with Gas Chromatography BAC results

The top 2 problems seen with Gas Chromatography BAC results The testing method used most frequently in blood based Blood Alcohol Content (BAC) analysis in the United States is called headspace gas chromatography (GC) with flame ionization detector, using wall coated open tubular capillary columns. The process analyzes chemicals without decomposing them.   The GC […]

Stereoselectivity matters in methamphetamine: The Science of Breaking Bad cook makes both D and L forms of meth

Methamphetamine analysis comes down to the stereoselectivity capabilities in the crime laboratory. Stereoselectivity is crucial in a crime laboratory. The ability of an analytical chemistry device to be specific to a type of a form of drug is key. Stereoselectivity is one of those key functions. Even the venerable workhorse of analytical chemistry in a crime […]

DEA: If you can’t win by the science, win by changing the rules…

If you are a Star Trek fan, then you will remember Kobayashi Maru scenario.   Wikipedia has a good description for you non-Star Trek fans. In Star Trek II: The Wrath of Khan, the simulation takes place on a replica of a starship bridge, with the test-taker as captain and other Starfleet members, officers or […]

How impossible courtroom testimony comes to be: the Colorado Department of Public Health and Environment Laboratory case study

Colorado Department of Public Health and Environment Laboratory crisis that concerns blood ethanol content by HS-GC-FID teaches us yet again the critical role that education plays in the training of analysts. People in the laboratory are just taught to press buttons and preform tasks. They are not experts. Anyone who has been in a courtroom […]

Chemical Measurement Process and The Calibration Function: How to best calibrate an instrument used in forensic science

The technical goal of any calibration related effort is t0 achieve a meaningful and valid CMP. According to The International Union of Pure and Applied Chemistry (IUPAC): Chemical Measurement Process (CMP): An analytical method of defined structure that has been brought into a state of statistical control, such that its imprecision and bias are fixed, […]

Retention of Biological Samples: In a DUI case, how long is long enough?

Suppose the following: You are driving home. You get stopped by the police. You are arrested for DUI. You are requested and give a sample of your blood. The blood goes to a laboratory and is analyzed. The results get transmitted to the police a few days later. The  police type it up a few […]

The Demonstrated Linear Dynamic Range Challenge in PA DUI Breath Tests

“You gotta prove it before you can use it, and then prove it again.” Would you use a pacemaker in a loved one if it wasn’t proven to work correctly before you used it? Would you use a baby car seat with your child if it wasn’t proven to work correctly before you used it? […]

Doughnuts and Blood Testing – How the government’s own data often proves that they contaminate blood samples and look the other way

The Colorado Springs Independent recently published an article about laboratory concerns within the Colorado State crime laboratory system. The article written by Chet Hardin was called “Blood and circus: Why many DUI lawyers don’t trust the state’s drug lab.” One of the issues discussed was the problem of ethanol being detected in blanks. The governments position of […]