DUI arrests are divided into three separate phases. The initial phase of the DUI arrest is referred to as "vehicle in motion." Law enforcement officers are trained to observe an individual's driving pattern and look for "clues." Quite simply, a clue is an indication that a driver is impaired. Officers are trained in the statistical correlation between the various clues and impairment. All clues are not equal. Some carry a high correlation to impairment and some have a low correlation. When evaluating a driver for a potential DUI traffic stop, an officer is trained to look for 24 separate clues that are recognized by the National Highway Transportation and Safety Administration. ("NHTSA") The clues are divided into four categories. 1) Problems maintaining lane position; 2) Speed and breaking problems; 3) Vigilance problems & 4) Judgment Problems. Often, a police officer will either misinterpret the NHTSA guidelines in order to effect a traffic stop or make a traffic stop for an infraction that is not included in the NHTSA guidelines. An officer must have probable cause that a driver is under the influence or witness a violation of a traffic law in order to make a stop. The distinction is important because if an officer asserts that he made the traffic stop based on probable cause, the officer does not have to allege that he observed the driver breaking any laws. Commonly alleged clues of impairment Many times an officer will allege in a traffic report that the defendant was "weaving" or crossed over lane lines as a pretext to making a DUI traffic stop. An officer may have probable cause to stop a vehicle for a DUI if he followed the car for some distance and the vehicle crossed the lane lines multiple times. This would be considered a driving pattern witnessed over a period of time that is consistent with a DUI case. However, under Florida Law, crossing lane lines in and of itself is insufficient to make a traffic stop. The reason being is that in order to be a traffic infraction, the crossing of the lane lines must interfere with other traffic on the road. Sometimes officers do not state in the police report whether the officer is making the traffic stop based on a probable cause of DUI standard or a reasonable suspicion of a traffic infraction standard. In order to determine whether the officer had the requisite level of proof to make the traffic stop, it is necessary to read the police report, view the dashboard video and question the officer in a deposition. It is possible to have evidence of your DUI charge suppressed if the stop was determined to be in violation of the 4th Amendment made applicable to the State through the 14th Amendment. Failure to signal a turn or a lane change is also considered a clue of impairment. Yet, under Florida Law, it is only legally necessary to signal a lane change if the lane change will impact traffic. Standing alone, a failure to signal for a lane change that does not interfere with traffic is neither a traffic violation or probable cause to suspect a person of DUI. The reason being is that a one time lane change, with no effect on traffic without signaling is perfectly normal and legal behavior. Common Traffic Violations That Are Not Clues of Impairment Frequently, a police officer will make a stop unrelated to suspicion of DUI. In the four categories of clues listed above, the second category is "speed and breaking problems." This is broad area, but the officer's discretion is not unlimited. NHTSA is very specific with what type of speed and breaking problems are necessary in order to constitute a clue indicating a DUI. Regarding the speed clues, NHTSA enumerates three clues that are possible indicators of a DUI. 1) accelerating for no reason; 2) varying speed & 3) slow speed. Frequently, police officers will state something similar to this in their reports, that a "defendant accelerated rapidly from a stopped position once the light turned green." This is not an clue for a DUI. There is a salient distinction between accelerating for no reason and accelerating because a traffic light turned green. The clue for DUI is not accelerating rapidly, it is only accelerating for no reason. Varying speeds is a repeated fluctuation of speed over a period of time. Slowing down for a turn, only to realize it is not the correct street, and then speeding up again is not an indication of a DUI. NHTSA defines slow speed as 10 miles per hour under the speed limit or more. It is important to note that NHTSA does not consider fast speed an clue for a DUI. Although speeding is a valid basis to make a traffic stop and may lead to a DUI arrest, it is not an indication to the officer that the driver is impaired.