KOCHI: Kerala High Court has directed the Director General of Police to issue necessary directions requiring the police officers concerned to ensure that ‘Air Blank Test’ is conducted and ‘0.000’ reading shown on the instrument before subjecting a person to a breathalyser test for drunken driving. The court said that the primary goal of a blank test is to verify that the breathalyser is functioning correctly and is not influenced by any residual alcohol from previous tests. Therefore, it is mandatory to conduct an Air Blank Test and ensure that the calibration is at ‘zero’ before taking a breath sample using a breath alcohol testing device.
Justice V G Arun issued the order while quashing a case against Saran Kumar S of Thiruvananthapuram. The case was registered on the allegation that the petitioner was found driving his scooter at approximately 8:30 pm on December 30, 2024, on the Medical College-Kumarapuram Road in a rash and negligent manner. The vehicle was intercepted by the police, and on suspicion that the petitioner had consumed alcohol, he was arrested and later released on self-bond after conducting a breathalyser test.
The petitioner argued that the printout of the breathalyser test produced along with the final report shows the reading in the blank test conducted, immediately before the petitioner’s breath sample was taken, as 412 mg/100 ml. It is submitted that the police were bound to ensure that the calibration of the device showed ‘zero’ before conducting the breathalyser test. Hence, no sanctity can be attached to the test conducted.
The court said that the primary goal of a blank test is to verify that the breathalyser is functioning correctly and is not influenced by any residual alcohol from previous tests. The Directorate General of Civil Aviation (DGCA) has made it mandatory to run an Air Blank Test on the instrument and obtain the reading ‘0.000’ before each breathalyser test.
The court held that the authenticity and acceptance of the breath analyzer test in evidence are dependent on the blank test reading being at ‘0.000’ when the test was conducted.
The court was informed that the policemen conducting the test are not aware of the requirements. Hence, the court directed that a copy of the court’s order be forwarded to the State Police Chief for necessary action.
The court said that in so far as the blank air test reading was 412 mg/100 ml when the petitioner’s breath sample was tested, no reliance can be placed on the alcohol content recorded in that test.
As the petitioner was not subjected to a separate medical test, there is no acceptable evidence regarding the alcohol level in his blood. In such circumstances, prosecution for the offence under Section 185 (driving under the influence of alcohol or drugs) of the Motor Vehicles Act will be an exercise in futility, said the court.
Breathalyser test
A breathalyser is a diagnostic device that measures the content of alcohol in the air a person breathes out
The purpose of conducting an Air Blank Test is to check for any residual alcohol before taking a breath sample from a person using a breath alcohol testing device
The primary purpose of an Air Blank Test is to avoid wrong results during the breathalyser test. If alcohol remains in the device from a previous test, it could falsely elevate the subsequent test result of another individual