The DWI stop is one of the key steps in a driving while intoxicated case. In order for a DWI arrest to occur, a driver must be stopped by law enforcement first. In New Hampshire, there are two ways that a driver can be stopped by police. The first is during a random sobriety checkpoint. This involves roadblocks that are set up by police with the intention of randomly stopping drivers passing through to check for seatbelt use, license and registration and also to look for signs of intoxication. The second is to stop a vehicle for probable cause. In New Hampshire, a law enforcement agent can only pull over a vehicle if they have probable cause that a crime is being or was committed. Most commonly, this occurs when an officer witnesses a vehicle breaking a traffic law such as speeding, failing to stop for a stop sign or driving with a broken headlight.

In some cases, an officer can stop a vehicle if they notice that the driver is demonstrating signs that they may be under the influence of drugs or alcohol. These cues include witnessing a driver traveling at reduced speeds, failing to signal or weaving in between lanes. Often, an officer who notices these signs will pull over the vehicle in order to determine the driver's sobriety. A key part of DWI law is that officers need a probable cause to stop drivers. For example, a police officer cannot set up outside of a bar on Saturday night and stop all drivers seen leaving the parking unless they witness the driver making some sort of error.

In order to catch as many DWI drivers as possible, police sometimes resort to using any slight driver error as means to stop them. For example, Penn Live reports that the Supreme Court in Pennsylvania recently ruled that even throwing a cigarette butt out of a car window can be grounds for a police stop. In July of 2011, a 61-year-old man named James Amatucci was driving down the road in Pennsylvania when he flicked a cigarette butt out of his car window. He was then stopped by an officer who witnessed this act stating that he initiated the stop on the grounds that Amatucci had violated a state law preventing citizens from littering.

During the stop, the officer found that Amatucci had a blood alcohol concentration over the legal limit as well as a small bag of cocaine in his vehicle. Additionally, Amatucci was driving on a license that was suspended for a prior DUI conviction. While Amatucci did appear to be in violation of several laws and could have been a threat to others on the road, the case centers around whether or not the stop was legal. In the U.S., criminal charges that result from a traffic stop with no probable cause will be dismissed no matter how severe the crime.

The Supreme Court ultimately ruled that one cigarette butt is enough to be considered scattering rubbish and, therefore, the stop was valid. However, one judge, Christine Donahue found the ruling troubling. In her dissenting opinion she argued the following:

The majority's ruling "provides law enforcement with (grounds for) pretextual motor vehicle stops" if police officers can say a driver tossed something, be it a cigarette or a gum wrapper, out the window, Donohue argued.

"It is unlikely that the Legislature intended such an insignificant action, done by so many on a frequent basis, to open the door for police to stop a vehicle," she wrote.

If law-enforcement agents are allowed to stop drivers for, as Judge Donohue wrote, “insignificant actions”, this could lead to drivers being stopped a lot more often and unexpectedly. Though littering is a crime, something as minor as tossing a gum wrapper out a window is not evidence that the driver may be committing further crimes or that their state is in some way impaired. Using this case as a precedent could give police the authority to stop many drivers that simply driving home late at night on a weekend (times when DWIs are most likely to take place).

This ruling, however, does not mean that all types of police stops are legal. If you have been arrested for DUI in New Hampshire and have questions as to whether the officer had probable cause to stop you, contact an experienced DWI attorney right away. If there was no probable cause for you to be stopped, a lawyer may be able to get your charges dismissed.