A Minnesota DWI Defense Lawyer Explains DWI Investigations
Reasonable suspicion, the standard of evidence for the stop, is much lower than probable cause, the standard of evidence for the arrest. For example, circumstantial evidence like bloodshot eyes usually only proves consumption, at best. For DWI charges to hold up in court, police officers need additional evidence. In most cases, the field sobriety tests provide the necessary proof.
Most field sobriety tests are based on the scientific principle that a brain under the influence of alcohol is incapable of multitasking. Intoxicated individuals can understand and apply a set of instructions and they can walk a straight line, but they cannot do both at the same time.
Nevertheless, not all FSTs are scientifically approved. One example is Romberg’s balance test. This is the head back, arms extended, and eyes closed test. There are several variations of this test, such as the finger-to-nose add-on.
These tests don’t necessarily prove impairment, and in some situations they can hurt the state’s case. Romberg’s test relies on a number of very complex scientific principles, such as proprioception, ataxia, and vestibular function. Most police officers are unfamiliar with these concepts. If they cannot explain them to jurors, they may conclude that the police officer doesn’t actually understand the test and that they are not reliable.
Most police officers know that the Romberg test and other unapproved tests have little evidentiary value. But they make defendants perform them, so the defendant is mentally and physically fatigued when the officer administers approved tests. There are four such tests in Minnesota.
Horizontal Gaze Nystagmus
The DWI eye test is usually the first test administered, and it’s also usually the most critical one. As mentioned, defendants have a Fifth Amendment right to refuse to perform field tests.
During this test, officers have subjects track moving objects using only their eyes. If the subject’s pupils move involuntarily at certain viewing angles, the subject probably has nystagmus. And, alcohol intoxication causes nystagmus.
However, alcohol is not the only cause of nystagmus, a condition also known as lazy eye. In fact, alcohol is not even the leading cause of nystagmus.
Furthermore, the HGN test is only accurate if it’s conducted under controlled conditions. Roadside HGN tests do not feature controlled conditions. Typically, the sky is dark and flashing squad car lights dance in the distance.
Walk and Turn
The walking-a-straight-line test is perhaps the most recognizable DWI field sobriety test. Defendants must walk a straight line, heel to toe, forward and backward, without using their arms for balance.
Some intoxication clues include beginning the test too early, starting with the wrong foot, failure to walk heel to toe, taking the incorrect number of steps, and ending the test early.
Once again, test conditions play a role in the result. Very few surfaces are perfectly flat and level. Furthermore, it’s much easier to walk an actual line, like a parking lot stripe, as opposed to an imaginary line. Footwear is an issue as well. Unless the subject is wearing athletic shoes, it’s almost impossible to complete this test.
The OLS is much like the WAT. Defendants must elevate one leg for about thirty seconds without swaying. Intoxication clues include holding the leg at the wrong angle, using arms for balance, and putting the leg down too early.
At trial, it’s not enough to show that the defendant “failed” the test. The state must prove, beyond a reasonable doubt, that the defendant failed the test because s/he was intoxicated, and not because s/he was sleepy, nervous, fatigued, or clumsy.
Minnesota is one of the only states where officers administer these tests. These gadgets have a number of technical and scientific flaws, as outlined below.
DWI-drug cases often have a different dimension. Since there is no Breathalyzer test for drug use, at least not yet, prosecutors often use Drug Recognition Experts to bolster the evidence of intoxication.
DREs are not really “experts.” They are police officers who completed an additional certification course at a police-sponsored seminar. DREs usually testify that, based on the FST results and some physical symptoms, such as glassy eyes, the defendant was under the influence of drugs. These conclusions are dubious, at best.