HARLINGEN — “No probable cause.”

Not exactly what a police officer wants to hear after making an arrest, but sometimes, DWI cases fail under the scrutiny of a judge.

“It doesn’t happen often, but his job is to evaluate for a probable cause, and if it’s not there, he will dismiss it,” said Harlingen Deputy Police Chief Myriam Anderson.

“If he decides, ‘Well, I’m not going to approve this case’ then the individual will be released,” Anderson said. “But the system will retain that paperwork of the DWI. In our PD database we will show ‘dismissed.’”

So what is probable cause?

“We need to have probable cause in order to place somebody under arrest,” Anderson said. “We have a process in which once somebody is arrested, we document the clues that indicate somebody was under the influence.”

Anderson said if the individual performs poorly the officer concludes he is under the influence of something, which can include alcohol or other drugs.

“Other indicators can be the smell of alcohol on the breath. It can be open containers in the car, or it can be by admission during the field interview for somebody that say, ‘Oh, yeah, I had a couple of beers,” she said.

Officers also consider other factors for someone driving incorrectly, such as a medical condition.

“If the person is not under the influence, if they’re having a diabetic attack which does happen, then we can call an ambulance and have the person checked out,” she said.

If the person is determined to be under the influence, officers can request a warrant from a judge to draw the individual’s blood to determine the blood/alcohol level. This is called a blood warrant, and officers must provide evidence of probable cause.

“This is where I have to document what I did, how the person performed, and the reason why I am asking for the blood warrant,” she said.

However, even after finding a high alcohol content in the blood, the case must still go to court.

“Once you go to court, the DA has to prove the case beyond a reasonable doubt,” she said. “That’s when they’ll present the case in front of a jury. The jury may say, ‘Yes, I agree with you. We’re going to find this gentleman guilty.’”

Many times, however, it’s not quite that simple.

“The defense attorney may present other information such as he was diabetic, and if he’s convincing enough and the jury buys it, then he was diabetic and he’s free,” she said. “I’m sure there are hundreds of reasons.”

Standardized Field Sobriety Test


Definition: The Standardized Field Sobriety Test (SFST) is a battery of 3 tests performed during a traffic stop in order to determine if a driver is impaired. The 3 tests that make up the SFST are the horizontal gaze nystagmus (HGN), the walk-and-turn, and the one-leg stand tests. Developed in the 1970s, these tests are scientifically validated, and are admissible as evidence in court in a majority of states.

The horizontal gaze nystagmus (HGN) test: Horizontal gaze nystagmus is an involuntary jerking of the eyeball which occurs as the eyes gaze to the side. Under normal circumstances, nystagmus occurs when the eyes are rotated at high peripheral angles. However, when a person is impaired by alcohol, nystagmus is exaggerated and may occur at lesser angles.

In the walk-and-turn test, the subject is directed to take nine steps, touching heel-to-toe, along a straight line.

In the one-leg stand test, the subject is instructed to stand with one foot approximately six inches off the ground and count aloud by ones beginning with one thousand (one thousand-one, one thousand-two, etc.) until told to put the foot down.