Breathalyzer, Blood, Urine, Field and Sobriety Tests

Law Offices of James Crosby Dec. 2, 2020

Just because a breathalyzer, blood, or urine test indicates you have a blood alcohol content (BAC) above the legal limit does not necessarily mean that: 1) it’s accurate; 2) the officer was legally justified in giving you the test; 3) the test was conducted properly; and 4) the results are admissible in court. In order to give you a test of some kind, a police officer first needs to conduct a field sobriety test after reasonable suspicion justifies him pulling you over in the first place. If an officer believes you might be drunk, he can administer field sobriety tests to establish probable cause to arrest you for DUI. If the field sobriety test is not administered properly, the DUI charge against you may be dismissed. And if it can be shown that the officer did not have reasonable suspicion to pull you over in the first place, your DUI charge may be dismissed as well.At the Law Offices of James Crosby,, we understand how to identify and expose mistakes on the part of police officers and medical experts who conduct forensic tests that compromise the validity of a DUI arrest. To discuss your DUI arrest and possible defenses for your case, contact our experienced DUI defense attorneys today.

Field Sobriety Tests

Field sobriety tests are used to determine if a police officer has probable cause to arrest you for drunk driving. Most police departments use the National Highway Traffic Safety Administration (NHTSA) DWI Detection and Standardized Field Sobriety Testing Student Manual as a standard for giving field sobriety tests. The manual lists countless instructions for what an officer is supposed to do if a suspect raises their arms more than six-to-eight inches, if the suspect stops momentarily, or if the suspect shifts their balance to one leg. There are additional instructions regarding the horizontal gaze nystagmus (HGN) or eye test and how the straight line walking test should be conducted and evaluated. Additionally, a field sobriety test should be given on a level, dry surface. If the test was administered on an incline, near broken pavement, or during inclement weather, it may be ruled as inadmissible at trial.

Breathalyzer Tests and DUI Arrests

Most Pennsylvania police departments use the Intoxilyzer 5000 to conduct breathalyzer tests. The Intoxilyzer 5000 operates according to Henry’s Law that assumes a blood alcohol ratio of 2,100 parts to every one part of blood. In recent years, a number of forensic experts have called into question the reliability of the Intoxilyzer 5000 and have demonstrated how mouthwash or the use of certain medications can register a false-positive under the Intoxilyzer 5000. Additionally, if the mouthpiece is not changed between breathalyzer tests or if a suspect is not observed 20 minutes prior to the test, the results may be unreliable and/or inadmissible. Further, like any piece of equipment, breathalyzers must be properly maintained and calibrated regularly. If the breathalyzer used in your DUI arrest wasn’t maintained as scheduled, the breathalyzer results may not be reliable.

Blood Tests and DUI Charges

When a blood test is administered, a suspect is typically taken to a hospital. Pennsylvania law requires that the testing center must be certified and follow specific procedures. By law, a blood test should be given within two hours of a person’s arrest. While blood tests are more reliable than some other types of tests, they too can be tainted: Did the person taking your blood wipe your arm with alcohol first? Was a blood test kit used? If so, was it expired? When the sample was taken, was it composed mostly of plasma or whole blood?

When blood is taken, drugs may also be found in the sample. However, since traces of drugs can show up in a blood test weeks after you last used them, just because you tested positive for illegal drugs doesn’t mean that you were Driving Under their Influence (DUI). Nonetheless, in Pennsylvania, any amount of illicit drugs found in your system will result in a DUI charge. For this reason, it’s essential to contact an attorney who can discuss your case and the options available to you.

Urine Tests and Drunk Driving Charges

Since water can remain in a person’s body over a long period of time, urine tests are not as accurate as blood or breathalyzer tests. This is especially of concern in cases where a person’s BAC is near or slightly over .08 percent, the legal limit for most drivers in Pennsylvania. However, urine tests can detect the presence of drugs in a person’s system. Unfortunately for a suspect, certain over-the-counter medications can trigger a false-positive reading for drugs. When that happens, it’s necessary to work with an experienced DUI attorney who understands the shortcomings of urine tests and who knows how to call their results into question.

Contact Pittsburgh, Pennsylvania DUI Defense Attorney James Crosby

Our attorneys understand the forensic issues involved in blood, urine, and breathalyzer tests. We also make a point of checking the site of a field sobriety test to see if it complies with the standards as set forth in the DWI Detection and Standardized Field Sobriety Testing Student Manual. If you’ve been arrested for a DUI offense, don’t assume that you don’t have any options – contact DUI defense lawyers at the Law Offices of James Crosby today.