In California, there are several types of sobriety tests that can be
administered to help officers figure out if you are DUI or not. When
the police initially stop you, they are likely to use either field
sobriety tests, passive alcohol sensors or both to try to determine if
you've been drinking and the degree of your impairment.
Field sobriety tests consist of a series of tasks that test balance,
coordination, and the ability to juggle multiple tasks at once. The
officer can administer whatever tests he or she chooses, but the most
commonly used tests are the three recommended by the National Highway
Traffic Safety Administration. These are the walk-and-turn, the
horizontal gaze nystagmus, and the one-leg stand. You’ve probably seen
some unlucky individual trying to perform these tests on the side of a
highway-attempting to stand on one leg, attempting walk a straight
line, or trying to follow an officer’s pen with their eyes. These tests
have an accuracy rate as high as 77% for the horizontal gaze nystagmus
and as low as 65% for the one-leg stand.
A passive alcohol sensor is like a breath test for alcohol that you
don't have to breathe into. It detects alcohol on your breath from a
short distance away from your face. Some police officers even have
passive alcohol sensors hidden on their flashlights. Passive alcohol
sensors are used to determine if there is probable cause to arrest you
for California DUI.
California police officers may also request that you breathe into a
portable breath testing machine, called a preliminary alcohol screening
test, or PAS test. These machines are not admissible in court, but a
high reading on a PAS test will provide probable cause for an officer
to arrest you and have you do a more accurate breath alcohol test at
Once arrested for California DUI, you have the option of providing a
breath test, blood test or urine test. Most police stations are only
equipped with a machine for the breath alcohol test. However, breath
alcohol tests are not completely reliable. They are calibrated for an
average person, and don't take into account natural variations between
the amount of alcohol that shows up in people's breath and the amount
that's actually present in their bloodstream. You do have the right to
get your own blood sample taken for later independent analysis, and the
arresting officer should advise you of this. However, there is no
penalty if the police don’t tell you. Since the breath test is not
always reliable, you should insist on having a blood test done and a
separate sample saved to be analyzed later.
If you refuse the test, you have violated California’s implied consent
law. Basically, any time you put your key in the ignition and start
your car, you are giving your consent to provide a chemical test if a
police officer requests it of you.
What about personal sobriety tests? These little contraptions claim to
give you an accurate reading of your BAC, so you’ll know if it’s safe
to take the wheel or not. Should you trust them? Not necessarily.
Depending on the model, personal sobriety tests can sometimes produce
readings that skew high or low. That’s not a problem if you’re just
checking to see how drunk you are as part of a fun party game, but it
is a huge problem if you’re relying on the test to determine whether or
not it’s safe and legal for you to drive. If the machine reads even a
couple of percentage points too low, or if you test your breath too
early in the game, before all of the alcohol in your stomach has had
time to reach your bloodstream, you could be in trouble. Saying that
you checked your BAC before driving with a personal sobriety test will
not get you out of trouble if the cops pull you over later and get a
higher reading on their machine.