How Do You Win a DWI/DUI Case? Probable Cause To Stop

Lack of probable cause may be a DUI defense and can get a case dismissed.

The second most popular question I get asked when people find out I am a DWI attorney is “how do you win a DWI or DUI case?”fn-1

The answer is there are a number of ways and you have to look at each individual case, but the simple answer is that I break the case down into:

  1. Did the police have probable cause to stop in the vehicle,
  2. Did the police have probable cause to arrest, and
  3. Did the police correctly test for Blood Alcohol Content (BAC).

Probable Cause

To keep this short I am only going to address the probable cause to stop issue, which has proven to be an extremely successful defense in a number of recent cases. Keep in mind that with the exception of sobriety check points (road blocks) and welfare checks (sleeping in a parked car) the police have to have probable cause to stop a person in their automobile. Probable cause to stop in a DWI/DUI case is that the person commits a traffic violation of some type or does something that would allow the police to investigate a possible crime. It can be as simple as burned out tail light, expired tags, or failure to signal a turn or as significant as speeding, weaving across the line into another lane of traffic, or an accident.

Police Testimony

Until a few years ago, every case was pretty much the defendant’s word against the police officer’s on whether there was probable cause. All you could rely on was the police officer’s testimony and report, the defendant’s testimony of the events, and if you were lucky you might have eyewitness testimony. Almost all police officers are trained on how to “correctly” write a report to highlight the facts and it doesn’t usually take an officer a long time on the force to get experienced at testifying in court. Your average DWI defendant on the other hand doesn’t get the chance to make any notes after being arrested and has never been to court in his life except to perhaps pay a speeding ticket. Obviously this gives the advantage to the police, especially when combined with the general notion that the police are supposed to be honest and unbiased servants protecting the public. In other words, when the police officer said a defendant was speeding, weaving over the line or made a wide turn, probable cause to stop the defendant was all but a given.

Video Evidence

With the advent of mobile video in the patrol cars this changed a few years ago as we were able to get a brief view of the defendant’s driving from the time the video was activated. Usually the video was activated when the blue lights were turned on and continued recording until manually turned off by the police officer. The video often would confirm the police officer’s statements if the bad driving continued after the blue lights were turned on, but occasionally the video would show the defendant driving in a perfect straight line, using his turn signal to pull over, safely pulling into a parking lot, and parking squarely between the lines of a designated space. On those rare occasions when the video captured such perfect driving I would argue no probable cause to stop and move to have the rest of the evidence suppressed. Usually, on these cases, the judges would deny my motion, but pay very close attention to how the defendant performed the Standardized Field Sobriety Tests and if the defendant did reasonable, but failed to provide a BAC sample (Blow) then I almost always walked out of the court room with an acquittal. fn-2

New Digital Recording

Recently, the major police agencies in my jurisdiction have gone to a real time digital recording system in their patrol cars. Much of the functionality of the digital recording system has been turned off, but the system does have a couple of features that are very helpful when evaluating a case for probable cause to stop. The majority of the digital recording system in use have been set to automatically back up and save the video from thirty seconds before the blue lights are activated. This thirty second window gives a much better indication of whether there was any bad driving before the defendant knew the officer was attempting to pull him over, thus negating the prosecutor’s usual argument that “of course he was driving fine in the video judge, he knew the police were pulling him over”.

Disproving Police Reports

In a number of my recent cases the police stated in their report things like “at 2:15 a.m. I observed the large black SUV make a wide left turn from Maple onto Leverett crossing into the oncoming turn lane and almost striking the front bumper of an automobile that was entering the turn lane”. The report went on to detail how the defendant had failed the SFSTs, smelled of alcohol, had blood shot watery eyes, slurred speech, was stumbling, and refused to submit a breath sample. On paper this sounded like a 100% guaranteed conviction, but I always take the time to review the video for anything that might be of help and this was one of those cases why I do.

Even though it was 2:15 a.m. there was enough light for the video to clearly show that the defendant did not even touch the yellow line marking the turn lane and the automobile coming from the other direction did not even enter the turn lane until after the SUV was a 20 feet down the street. There were also a number of other issues in this particular case, including the officer incorrectly demonstrating the SFSTs, the defendant’s passing the tests when the office said he did not (improper interpretation of the tests), and the officer’s improper use of the Intoximeter EC/IR resulting in an additional charge of Violation of the Implied Consent Law (failure to submit a BAC sample). These issues were much more technical and a lot harder to get a judge to grasp, but in this case they never were a factor because without the alleged traffic violation the judge found that there was “no probable cause to stop the defendant” and all of the evidence after the stop was inadmissible. What started as a certain conviction on paper turned into a quick and easy “not guilty” for the defendant with a review of the video. fn-3

Other Data Available from Video

The digital recording system has also been very helpful in that it provides other data that I have been using to review probable cause for the stop, such as a continuous time stamp and when the police officer uses the brakes. With the use of the county survey maps showing the exact distance between all streets and the continuous time stamp allow me to calculate defendant’s speed between two known points. When the police officer says he verified by radar that the defendant was speeding and weaving, and the video does not show the radar readout and shows no weaving it is pretty easy to get an acquittal if you do the time distance calculations.

So I always check the video and see if I can nip the case on the front end with a motion to suppress all evidence based up the police not having probable cause to stop the defendant in the first place.

Video from the Case

© 2010 Paul D. Reynolds, Atty.

fn1 - The most common question I get asked is “should I blow if arrested for DWI?” The short answer is it depends. For a more in-depth answer take a look at my FAQs page at
fn2 One of our local small town police agencies went so far as to remove their video equipment from their patrol cars because they were losing too many DWI cases. Interestingly, the video equipment had been purchased with a federal grant for the purpose of protecting the police from allegations of impropriety and to enhance the department’s conviction rate. After several “not guilty” verdicts the equipment was removed from the patrol cars and sold to another police agency. It is my understanding that the grant money was not refunded to the federal agency that provided the grant. How is that for an example of how your tax dollars used.