Common Police Mistakes


And how they can help you

Liberty may be endangered by the abuse of liberty

but also by the abuse of power.


Numerous policies, procedures, and laws govern the actions of the police. Mistakes, misunderstandings, or errors from the initial contact to the final booking may help in winning your DWI.

Improper Stops

TIPS OR ANONYMOUS CALLS – For most DWI cases, an officer cannot stop you based solely on an anonymous call. The officer must observe an actual violation of the law before the stop is legal.

MISTAKE OF LAW – Even if the officer has the best intentions, a stop based on a mistake of law is an illegal stop.

WEAVING IN LANE – This observation alone is not a proper basis to stop a driver. No car drives completely straight. There are various reasons a driver may drift or weave within a lane.

STOPPING WRONG CAR – Just as an officer must see an actual violation, the officer must be able to clearly identify the car stopped and identify why it was stopped.

STOPPING FOR A HUNCH OR JUST FELT LIKE IT – Rarely will an officer admit this was the reason for a stop. Almost every officer knows this is an illegal stop and any resulting evidence will be excluded.

Improper Arrest

BAD SFST – The roadside gymnastic tests are a tool used to make an arrest decision. The tests have specific rules and observations. If they are not followed, then any conclusion would be improper as the validity of the field studies is compromised.

WEATHER – Weather can affect observations of driving and performance on SFST’s. Failure to consider this factor can affect credibility. Some officers will administer HGN in the rain which can cause the eyes to jerk due to the rain drops hitting the eye or because of the light reflecting off the droplets.

MEDICAL-PHYSICAL CONDITIONS – There are numerous medical and physical conditions that can affect a person’s roadside behavior and performance. These issues should be considered and factored into an officer’s arrest decision. For instance, there is documented court testimony of at least 38 causes for HGN (the condition being tested during the pen/eye test) other than alcohol related. Included are stress, caffeine, flu, strep, measles, hypertension, lack of sleep, and fatigue to name a few. There are also 47 types of Nystagmus which the officer cannot differentiate from alcohol induced nystagmus.

ILLEGAL EXTENSION OF STOP – Once an officer has completed the reason for the initial stop; he should terminate the contact and allow you to leave. For instance, if you are stopped for speeding, you should receive a ticket and be allowed to leave unless there is a clearly articulated reason to extend the detention. Once the officer writes the ticket he must release you unless he already has reasonable suspicion to investigate further.

PRIVATE PROPERTY– A DWI arrest is not normally proper if you are on private property that is not open to the public. However, recent case law allows officers to make an arrest within a gated community if he is able to enter the community legally.

VIDEOS DON’T SUPPORT ARREST REPORT– Many agencies use videos. You have probably watched COPS on TV. When the videos are available, they may not support the arrest decision or may show facts different from what is in the police report. The worst offense reports are those that cannot be backed up with a video because the arresting officer knows it is his word against the word of a drunk driver.

Improper Blood Test

PROPER REQUEST – There are specific reasons under the law for requesting and taking a blood test. If these are not followed, the test may be excluded.

STATUTORY REQUIREMENTS – There are specific procedures that must be followed in performing a blood test.

LAB MISTAKES – Most often a blood test is not tested by a human. Many samples are loaded in a machine; it runs overnight and prints out multiple reports in the morning. This is open to many human and machine mistakes.

Sample Tray at Lab

Improper Breath Test

Texas DPS Breath Test Program – A specific agency, the Texas Department of Public Safety, sets the rules governing all breath testing in the State of Texas. Failure to follow the rules will result in the exclusion of the test from court evidence.

CERTIFICATION – The operator of the machine must be certified and the certification must be renewed annually.

CERTIFICATION OF MACHINE – The machine must be certified and periodic maintenance must be performed on it.

INTERFERENTS – There are numerous chemical and physical items that can interfere with a proper test, which can result in false readings.

MACHINE NOT CALIBRATED – If a machine is not properly calibrated, it will result in false or unverifiable readings.

MACHINE MALFUNCTION – This machine is 1980’s technology. There are numerous parts of the machine that may not be working, yet, the machine will still generate a BAC reading.

PROCEDURES NOT FOLLOWED – There are specific procedures that must be followed before a proper test can be administered.

Procedural Mistakes

MIRANDIZE/READ YOUR RIGHTS – Although the law will not require a reading of your Miranda Rights, if the officer continues to question you after your arrest, many statements may be excludable.

WITNESS APPEARANCE – If a witness was responsible for your initial stop or other key element, the witness will also have to appear at key points in the case.

INCONSISTENT STATEMENTS BY OFFICERS– If the cop gives different stories in his report from later testimony, it brings his credibility into question.

EXPERT WITNESS – We have experts who often can analyze reports, breath tests, and video tapes to help determine if the arrest was proper and the facts are correctly presented.

ABSORPTIVE STAGE – It is a medical fact that during the early stages of drinking, you will show an artificial ‘peak’ while absorbing the alcohol. This means that during the early stages of absorbing alcohol—before it is fully absorbed into your system—you will yield an artificially high BAC.