Can a Substitute Witness Convict You Using Someone Else’s Lab Report?

By: John Guidry

Our government can be lazy. I know that statement may shock some of you, maybe offend others. But let’s be real: police work is only “easy” in a police state.

North Korea saves time and money. China saves time and money. Why even have the expense of a trial and a jury to begin with? Because in America, we have the Constitution, and specifically, the Confrontation Clause.

We all know that you cannot cross-examine a piece of paper. Yet, prosecutors constantly complain that bringing actual witnesses to court costs taxpayers too much money. They want to take shortcuts. They want to admit a lab report—essentially a piece of paper that testifies against you—without the actual human being who wrote it standing there to answer for it.

Trust me, I’m a Doctor (juris doctorate, that is, not a real Dr. like Dre). I know that when the government gets lazy with your rights, people go to jail who shouldn’t.

Facing a DUI or drug charge involving a lab report?

Don’t let a piece of paper determine your fate. Call John today at (407) 423-1117.

The Legal Breakdown: Bullcoming v. New Mexico

The fight over “forensic paperwork” has a history. First, the Supreme Court ruled in Crawford and Melendez-Diaz that the State cannot just hand a lab report to the jury and say, “Trust us.” They have to produce a witness.

So, prosecutors got creative. They started using “Surrogate Testimony.” Instead of calling the actual analyst who tested your blood or drugs, they would call “just anyone” from the lab to testify generally about how the machines work.

The U.S. Supreme Court put a stop to this in Bullcoming v. New Mexico, 131 S. Ct. 2705 (2011).

• The Problem: The State admitted a blood-alcohol concentration (BAC) report without the analyst who created it. Instead, they brought in a “surrogate”—a different guy from the lab who didn’t conduct the test but knew the procedures.
• The Question: Can you cross-examine someone about a test they didn’t perform?
• The Ruling: The Supreme Court administered a beat down to this lazy practice. They ruled that surrogate testimony violates the Confrontation Clause.
• The Reasoning: The Court recognized that lab analysts aren’t just filing clerks. Operating a gas chromatograph requires specialized training. If the analyst made a mistake—like using the wrong amount of chemicals or failing to calibrate the machine—a “surrogate” wouldn’t know that. Only the person who did the work can answer for it.

The Court even pointed to a Colorado lab that produced 206 flawed blood-alcohol readings over three years because an analyst messed up the machine settings. If a surrogate had testified in those cases, that fraud never would have been uncovered.

John’s Takeaways

This is heavy legal stuff, but it matters for anyone facing charges in Orange, Seminole, or Volusia County. Here is what you need to take away:

• Paper Can’t Be Cross-Examined: If the State tries to use a lab report against you without a witness, we object immediately. You have a right to face your accuser, even if that accuser is a lab technician.
• Surrogates Are Useless: A witness who says, “Well, usually we do it this way,” is not good enough. We need to know what happened in your specific case, not what happens “usually.”
• Machines Are Not Infallible: Prosecutors love to act like science is magic. It isn’t. Machines break, and humans make errors. As Bullcoming showed, labs can be “fertile ground” for mistakes and even fraud.
• CSI is Fiction: Real lab analysts aren’t the glamorous truth-seekers you see on TV. Often, these labs are run by the very police agencies trying to convict you. They have bias, and we have the right to expose it.

Make Them Do Their Job

The State has a burden of proof. It is not your job to help them save time or money; it is their job to prove you guilty beyond a reasonable doubt using admissible evidence. If they want to use a lab report, they better bring the person who wrote it.

If you are facing charges involving blood tests, drug analysis, or breathalyzers, you need a defense attorney who knows how to challenge the “science.”

Call me at (407) 423-1117. Let’s make them follow the rules.

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.