The Twelve Weeks of DRE-Mas: Dark Room Examinations

As I mentioned in an earlier post about the Drug Recognition Evaluation Program, there are a series of steps related to assessing an individual’s eyes. As we’ve already seen, the Horizontal Gaze Nystagmus and the Vertical Gaze Nystagmus tests are two such examinations, and each with their own set of flaws and reliability concerns. But there is more than meets the eye to the eye examinations in the DRE.

The next stage involves the assessment of the behaviour of a person’s pupils in response to various lighting conditions. I find this to be one of the more problematic aspects of the test, for reasons that will become clear in this post and in the coming weeks. So without further ado, here’s what happens when you and the officer go into a dark room together.


The purpose of the dark room examinations is to test the pupil’s reaction to various sources of light: total darkness, near darkness, and room light. Yes, you read that right. Room light. But look around you. The room you are in has a varied source of lighting. I am currently on a plane. The lighting conditions in my seat are different than those for the person next to me. There are various sources of light and the proximity to those sources, as well as the angle of proximity, all affect the condition of the light.

There is no standardization of how the lighting conditions are to be assessed for room light examinations. Police are not trained to ensure there is a minimum number of lumens present, or a maximum. This is inherently problematic. Let me explain the test.

The DRE officer has the person stand in “room light.” Then, using a highly scientific tool called a pupilometer, the DRE officer will measure the size of the subject’s pupils in that room light. Want smaller pupils? Add more light. Want larger pupils? Use less light. Heck – even try this with a friend. Move about the room and watch as pupil size changes in response to various lighting conditions.

After the pupil has been measured in the room light, the DRE officer will then turn off the lights to achieve total darkness. And then the longest wait of a person’s life begins. For about ninety seconds the DRE is trained to stand there in the total darkness conditions in order to give time for the eyes to adjust to the lighting conditions. This is a concern. I certainly would not want to be alone in a dark room with someone I thought was on drugs, nor would I want to be alone in a dark room with a police officer who thought I was on drugs. And without knowing what is happening, time ticks by very slowly for people in these conditions.

Once the DRE officer’s eyes have adjusted to the darkness, a light source — typically a pen light — is introduced to provide “near-total-darkness” in order for the assessment of the size of pupils. After this, the light source is shined directly into the subject’s eyes. Left first, then right. Measuring the reaction of the pupils to the light stimulus.

Pupil reaction to light can be impacted by any number of factors. For example, people who have had scleral buckle surgery will have different pupil responses to light. But another factor that hearkens back to last week can also affect pupil response: hypertension medication. Yes, some high blood pressure meds will impact the pupillary reaction. This is incredibly important because of the role that blood pressure also plays in the DRE test process. Damage to the optic nerve, or optic nerve and brain stem diseases or disorders can also cause changes in pupillary response.

Oh, and that pupilometer… the so-called highly scientific method to measure pupils? It is literally nothing more than a piece of cardboard with various sized dots printed on it, with measurements. The DRE officer literally holds a piece of cardboard up to your eyes and makes a visual estimate of pupil size. That is not a pupilometer. It is a piece of garbage, junk science nonsense that does not produce accurate or scientifically valid results. In case you were wondering, this is a pupilometer and it is a clinical tool used in emergency assessments and opthamology and optometry.

But hey, why bother equipping police with the tools necessary to make an accurate assessment of pupil size and reaction to light? A spot-the-difference cardboard scale is totally the same. Remember folks, the DRE officers are basically doctors anyway.

Oh, and one more thing.

After this evaluation is complete, lumped in to the assessment done in the dark room is an examination of the nasal and oral cavities for drug residue.

I’m not sure how many meth users are chewing on a shard of methamphetamine, but other than looking for cocaine dust (or drywall dust, or baking flour, or any number of white powders) on the inside of someone’s nose the presence of a residue does not really say much and isn’t really going to be expected. Nevertheless, one of the most important thing the police will be looking for in suspected cannabis-impaired drivers is the presence of a green tongue.

I kid you not. The police are actually trained to look for a green tongue, as though inhaling cannabis smoke will turn your tongue green. The best advice I can give any cannabis user is to quit eating any green-colored candies after legalization. Your green apple sour belt candy stains will be construed as proof positive that you’ve been tokin’ up before driving. I swear, with each step this test becomes more and more ridiculous.

So come back next week and prepare to have your mind blown about what happens after you’ve been held in a dark room and had bright lights shined in your eyeballs.

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