Blood Alcohol Concentration

Breath Testing Errors

Breath testing techniques such as a breathalyzer are definetely not an exact science. There are many factors that can cause inaccurate results, such as temperature, breathing patterns, and hematocrit (cell volume of blood). All are described below.
Temperature - A breathalyzer reading is often incorrect due to the fact that it can be sensitive… Read Full Post

Retrograde Extrapolation

To explain what retrograde extrapolation is and why it is needed, imagine that you have been pulled over for drunken driving. Knowing that you are drunk, you decide that it is in your best interest to refuse the breathalyzer test. In doing so, the police officer then puts you in the back of the car… Read Full Post

Progressive Effects of Alcohol

BAC (%)
Behavior
Impairment

0.01–0.029
-Avg. individual appears normal
-Subtle effects that can be detected with special tests

0.03–0.059
-Mild euphoria
-Sense of well-being
-Relaxation
-Talkativeness
-Joyous
-Decreased inhibition
-Lowered alertness
-Judgment
-Coordination
-Concentration

0.06–0.10
-Blunted Feelings
-Disinhibition
-Extroversion
-Impaired Sexual Pleasure
-Reflexes Impaired
-Reasoning
-Depth Perception
-Distance Acuity
-Peripheral Vision
-Glare Recovery

0.11–0.20
-Over-Expression
-Emotional Swings
-Angry or Sad
-Boisterous
-Reaction Time
-Gross Motor Control
-Staggering
-Slurred Speech

0.21–0.29
-Stupor
-Lose Understanding
-Impaired Sensations
-Severe Motor Impairment
-Loss of Consciousness
-Memory Blackout

0.30–0.39
-Severe Depression
-Unconsciousness
-Death Possible
-Bladder Function
-Breathing
-Heart Rate

>0.40
-Unconsciousness
-Death
-Breathing
-Heart Rate

Estimating BAC from Quantity of Drinks

Many people believe that after drinking a certain amount of drinks that their blood alcohol level is in the clear in that it is within the legal limit. Generally speaking, this is not a good measure. The reason this method should not be used is that calculating how drunk you are varies based on physiology… Read Full Post

Blood Alcohol Content (BAC) Formula

Blood alcohol content (BAC) is defined as the concentration of alcohol in blood. Most of the time it is computed as mass per volume, such as .08% really means .8% or .08 grams of alcohol per 100 grams of blood.
The following is a formula for computing the blood alcohol level:
1 g/kg = 1 g kg-1… Read Full Post

Texas DWI Field Sobriety Tests

In order to prove probably cause for a DWI arrest in Texas, police may ask a person to perform field sobriety tests. The purpose of the tests are to show abnormal use of mental or physical faculties. The manuals for these field sobriety tests are given by the National Highway Traffic Safety Administration (NHTSA). The… Read Full Post

Symptoms for Detecting Drunk Drivers

The following list contains symptoms that are used by police officers to detect drunk drivers. The list contains the symptom, followed by a percentage representing the chance that the driver’s blood alcohol content (BAC) is over the legal limit.

- Turning with wide radius: 65%
- Straddling center or lane marker: 65%
- Appearing to be drunk: 60%
-… Read Full Post

Determining Alcohol Concentration in Dallas Texas

Texas law provides that alcohol testing may be performed by analysis of a DWI suspect’s urine, blood or breath.
- Urine testing is the least accurate and least reliable means of alcohol concentration testing.
- Blood testing is thought by the majority of forensic scientists to be the most accurate and reliable means of alcohol concentration determination…. Read Full Post