Lab Rats and 15-Year Mandatory Minimums: The High Cost of Commingling

By: John Guidry

Just turn on your TV and take note of shows like C.S.I. and NCIS that deal with scientific evidence. Sure, some of this stuff is pretty far out; after all, it would be a boring show if all they did was fingerprint a crime scene and match the prints. Yet, scientific procedures in the real world rarely turn out to be as accurate as they’re portrayed on the screen. Even the simplest scientific procedures, like weighing evidence, can be completely worthless if not done properly.

For those familiar with Orlando DUI law, you might expect a challenge to the calibration of the scales or the certification of the chromatographs. But often, the problems arise out of pure and simple human error. Any Orlando criminal defense attorney can tell you: lab reporting problems are rampant. (I mean, does the weight a cop puts in the arrest report ever match the FDLE’s testing?)

Take the case of Purvis v. State, 43 So. 3d 734 (Fla. 2d DCA 2010). Purvis was convicted of trafficking in cocaine for possessing more than 400 grams—a charge that carries a 15-year minimum mandatory prison sentence.

Facing trafficking charges where the weight is close to a threshold? Don’t let a chemist’s “blabbing” about totals take your freedom. Call John Guidry at (407) 423-1117.

The Blending Disaster: Commingling Evidence

The problem in the Purvis case came down to how the chemist handled the evidence. There were five separate containers with a total of 27 separate baggies of cocaine. The state chemist decided to dump all of the cocaine from every container into one big pile. After mixing them all together, they tested the pile, and—surprise—it tested positive.

The Failure of Proof: Because the chemist blended the baggies together before testing them individually, the State could no longer prove that every bag contained cocaine. For all we know, 20 of those bags could have been baking soda, and only seven had actual cocaine. But once they’re mixed, we’ll never know.

While the appeals court initially denied the appeal because the trial attorney failed to object (another “sad but true” lesson on why trial experience matters), Purvis eventually won on an Ineffective Assistance of Counsel claim. The court cited several landmark “commingling” cases:

• Sheridan v. State (850 So. 2d 638): A trafficking conviction for powdered meth was reversed because two bags were combined before testing.
• Campbell v. State (563 So. 2d 202): A heroin trafficking conviction was tossed because the chemist only tested one or two capsules out of many.
• State v. Clark (538 So. 2d 500): A court affirmed that commingling tested and untested capsules prior to weighing violates a defendant’s Due Process rights.

The 2025 Reality: Trafficking Thresholds

As of 2024 and 2025, Florida has only intensified its focus on weight-based sentencing. With the rise of the HALT Fentanyl Act and new state measures, the difference of even one gram can be the difference between a few years and a lifetime.

John’s Takeaways

• Individual Testing is Mandatory: If the State wants to stack weights to hit a 15-year minimum mandatory, they must prove that each separate container actually contains the illegal substance.
• The “Mixture” Trap: Under F.S. § 893.03(2), the law allows the State to weigh the “mixture” (the drug plus the cutting agent), but it does NOT allow them to create their own mixture by dumping separate baggies together in a lab.
• Objections Matter: If your lawyer doesn’t object to the “lab science” during the trial, you might be stuck fighting an “ineffective assistance” claim from a prison cell for years.
• Human Error is Real: From the scale at the scene to the “commingling” at the lab, there are dozens of places for a “failure of proof” to occur.
• Regional Reality: In Orange, Seminole, and Osceola County, the FDLE labs are overwhelmed. Overwhelmed people make mistakes. We look for those mistakes.

The justice system is harsh, and it is “insane” to think that a chemist’s shortcut can cost a man 15 years of his life. I’ve been defending Central Florida citizens against “junk science” and lab errors since 1993. If your trafficking case involves a “total weight” from multiple containers, let’s see if the State actually followed the rules.

Facing a trafficking charge? Call John at (407) 423-1117.

About John Guidry II

John Guidry II is a seasoned criminal defense attorney and founder of the Law Firm of John P. Guidry II, P.A., located in downtown Orlando next to the Orange County Courthouse, where he has practiced for over 30 years. With more than three decades of experience defending clients throughout Central Florida since 1993, Guidry has successfully defended thousands of cases in Orange, Seminole, Osceola, Brevard, Lake, and Volusia counties. He has built a reputation for his strategic approach to criminal defense, focusing on pretrial motions and case dismissals rather than jury trials.

Guidry earned both his Juris Doctorate and Master of Business Administration from St. Louis University in 1993. He is a member of the Florida Bar and the Florida Association of Criminal Defense Lawyers. His practice encompasses the full spectrum of Florida state criminal charges, with a particular emphasis on achieving favorable outcomes through thorough pretrial preparation and motion practice.

Beyond the courtroom, Guidry is a prolific legal educator who has authored over 400 articles on criminal defense topics. He shares his legal expertise through his popular YouTube channel, Instagram, and TikTok accounts, where he has built a substantial following of people eager to learn about the law. His educational content breaks down complex legal concepts into accessible information for the general public.

When not practicing law, Guidry enjoys tennis and pickleball, and loves to travel. Drawing from his background as a former recording studio owner and music video producer in the Orlando area, he brings a creative perspective to his legal practice and continues to apply his passion for video production to his educational content.