When  a police officer makes a traffic stop, he or she may claim that the driver was clocked traveling above a posted speed limit or that the vehicle has a brake light that does not appear to be functioning properly. In many cases, however, the reason for a Maryland traffic stop is because DUI is suspected. It is common for a police officer to ask a driver under suspicion to exit his or her vehicle.

Once the driver is standing outside his or her car, the police officer may request that he or she perform a field sobriety test. Failing such a test may lead to a drunk driving arrest because a failed test constitutes probable cause, which an officer needs to take someone into custody. This is why field tests tend to make people quite nervous.

There are typically three types of field sobriety tests that police use to determine if there is probable cause to make an arrest. These tests include a one-leg stance, horizontal gaze nystagmus test and a walk-and-turn test. An officer might issue a failing grade if the subject puts his or her foot down too soon in a one-leg stance or if his or her eyes move erratically before reaching maximum field of vision when tracking an object horizontally or vertically.

A DUI arrest cannot be made as a mere consequence of refusing to take a field sobriety test. The fact is, such tests are not legally required in Maryland or elsewhere, and there are no penalties for refusing to comply. A police officer may not threaten to arrest someone if he or she will not submit to a field test. Being stopped for suspected drunk driving is a stressful experience but may be less so if a request for legal representation is made at the earliest possible opportunity.