How Police Determine if Someone Is Under the Influence of Drugs or Alcohol

One of the most serious accusations that an average person may ever face is a DUI charge. This raises the question of how the police determine whether or not someone was driving while under the influence of alcohol or another mind-altering substance. It is important to have an understanding of this so you can avoid getting into legal trouble. This guide will explain everything you need to know on the matter.

How an Arrest Is Made

In order for a police officer to determine if someone was driving while impaired and make an arrest, two things are needed:

• Reasonable Suspicion
• Probable Cause

If the officer does not have both of these things, it is unlawful for him or her to place a citizen under arrest. In addition to needing both reasonable suspicion and probable cause, he arresting officer needs to follow a particular process. The officer needs to have reasonable suspicion before he or she is allowed to investigate the citizen. Then an arrest can only be made if the investigation yielded probable cause. If an officer does not have both, or if reasonable suspicion is only found as a result of the investigation, then the charges will likely be dropped entirely.

Reasonable Suspicion and Probable Cause

So you now understand a bit about the process, but what exactly are reasonable suspicion and probable cause? They are both very easy to understand. Reasonable suspicion is simply a reason to be suspicious of someone. Evidence of a crime is not needed to investigate someone, but simply something that suggests a crime has been committed. In DUI cases, erratic driving, colliding with objects, or driving too fast or slow are examples of reasonable suspicion. They are not evidence of a DUI, but they are reason enough to pull a driver over.

On the other hand, probable cause is evidence of wrongdoing. Evidence is needed to place anyone under arrest. In DUI cases, the smell of alcohol on someone’s breath, drunken behavior, or a failed sobriety test are examples of probable cause.

So, to answer the original question, this is how an officer determines if someone is driving under the influence of alcohol: First, they notice suspicious behavior in order to pull a car over. Then, they must notice some piece of evidence that indicates that a person is drunk. Finally, the office may make an arrest. Even if probable cause is eventually found, if an officer pulls someone over without reasonable suspicion, charges will likely be dropped. Speak with a DUI lawyer in Fairfax, VA to learn more.

Thanks to May Law, LLP for their insight into criminal law and how police determine if someone is under the influence of drugs or alcohol.