Science, Faith, and the Black Box: Why the “Breathalyzer” Isn’t Always Right

By: John Guidry

Usually, this website discusses how our Constitution applies to we citizens from a boots-on-the-ground perspective. It’s nice that CNN and FOX News have law professors reading teleprompters about pie-in-the-sky Constitutional ideals, but rarely can the average citizen gain knowledge about how our laws truly operate without someone reporting from inside the war zone. (That’s me, fyi).

That being said, criminal defense work often requires a healthy skepticism of science, especially when it comes to the reliability of our government’s scientific instruments—like the Intoxilyzer 8000 used in DUI cases.

The prosecutors will march their experts into court and bedazzle the jury with their so-called “knowledge.” But very few judges and prosecutors have ever taken a close look at the flawed logic underpinning these conclusions.

Did a machine say you were drunk when you felt fine?

Science makes mistakes. Call John today at (407) 423-1117.

The Myth of “True Knowledge”

Science claims to have cornered the market on “true knowledge,” but religious folks would disagree, as would many mathematicians. Much of current physics sounds more like faith than fact, making claims about the existence of particles which have never been seen (quarks, for example). Sure, I realize that atoms are smaller than light waves, so there is no way we can see them directly. How convenient—as convenient as not being able to see the God I pray to, I suppose.

I get that, and that’s why it’s called faith. But the larger picture here is that the scientific method is not as ironclad as some cocky materialists would have you believe.

The Problem of Induction (The “Black Raven” Trap)

Science is based on a form of logic known as Induction. The Oxford Dictionary defines it as “the process of inferring a general law or principle from the observation of particular instances.” In other words: We guess based on patterns.

The Raven Example: In his book Labyrinths of Reason, William Poundstone explains it perfectly:

“You don’t know why all the ravens seen have been black. Even after seeing 100,000 ravens, all black, the 100,001st raven just might be white… There is no logical necessity to an inductive conclusion.”

Induction is founded on the hope that the world is not deceptive. We assume the unobserved ravens (the future) will be like the observed ravens (the past).

Newton and Gravity: Even Isaac Newton, the greatest mind ever, admitted this limitation. He developed equations that put men on the moon, but he couldn’t explain why gravity worked.

“I have not been able to discover the cause of those properties of gravity from phenomena, and I frame no hypotheses…” — Newton, Principia (1687).

If Newton wasn’t sure, why is the State of Florida so sure about a plastic box made in Kentucky?

The Gambler’s Fallacy and the Intoxilyzer

This leads us to the Gambler’s Fallacy. If I flip a coin 10 times and get “Heads” every time, you might assume the next flip must be “Tails” (or “Heads” again because the streak is hot). The Truth: The coin has no memory. The odds reset every time.

How This Applies to DUI Cases: The State argues: “This Intoxilyzer machine worked correctly the last 50 times we tested it in the lab; therefore, it must have worked correctly when you blew into it.” That is the Gambler’s Fallacy wrapped in a lab coat.

• Just because the “raven” was black yesterday doesn’t mean it isn’t white today.
• Just because the machine calibrated correctly last month doesn’t mean a power surge didn’t fry the sensor five minutes before your test.

John’s 2026 Update: The “Zombie” Machine Defense

Note: In 2026, the Intoxilyzer 8000 is ancient technology, yet it refuses to die.

1. The “Source Code” Black Box We still fight over the Source Code (the computer programming) of the Intoxilyzer 8000.

• The Issue: The manufacturer (CMI) refuses to release the full code to defense experts, claiming it is a “trade secret.”
• The Defense: How can we trust a machine if we aren’t allowed to see how it “thinks”? Using the Daubert standard (the rule for scientific evidence), we argue that a “secret” science is not real science.

2. The “Volume Not Met” Glitch One of the most common errors we see in 2026 is the “Volume Not Met” flag.

• The machine requires a specific amount of air (1.1 liters) to get a valid sample.
• We often see cases where the machine says “Volume Not Met” (meaning you didn’t blow enough) but still prints out a BAC number.
• The Argument: If the machine admits it didn’t get enough air to follow its own rules, how can it scientifically claim to know your alcohol level? It is guessing.

3. The “Authorized Repair” Scandal Florida courts (like in the Kilburn case) have thrown out results because the police sent broken machines to unauthorized repair shops.

• If your machine had a “unauthorized surgery” (like a new breath tube installed by a random deputy instead of a certified tech), the results are scientifically invalid.

Don’t Let “Junk Science” Convict You

If the State is trying to use a magical black box to prove you were drunk, we need to look under the hood. Their “science” is often just an educated guess.

Call me at (407) 423-1117. Let’s demand the proof.

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.