Probable Cause: “What is probable cause?”

Our Virginia Defense Attorney‘s 4th Amendment Probable Cause Introduction:
What is Probable Cause?

probable cause

“Probable Cause” (PC) is an intricate legal term that all criminal defense attorneys and regular citizens ought to be familiar with. Why should non-lawyers take a few moments to familiarize themselves with the 4th Amendment and PC? Simple. It has to do with our privacy interests.

As a Virginia Defense Attorney and
Fairfax Criminal Lawyer, I Study Trends

As a local Fairfax criminal lawyer whose law firm serves counties and cities in Northern Virginia, I instructed my research team to find evidence to demonstrate just how curious people are about learning about 4th Amendment rights…specifically, learning about probable cause. The data we analyzed revealed that every month more than 12,000 people use a popular search engine to look up terms related to “probable cause.”

By understanding probable cause and basic Supreme Court case decisions, it is possible for a charged individual to better understand his or her rights, defenses, and to determine whether or not police misconduct may be an issue. If you hire a lawyer to represent you for a criminal matter, he or she will normally ask specific questions to determine whether or not 4th Amendment issues exist; if a person’s 4th Amendment rights were violated and it resulted in law enforcement discovering evidence against the accused, a doctrine known as the “exclusionary rule” may apply and prevent the prosecutor from using that evidence at trial.

Some of the most frequently searched-for terms related to probable cause:

  • probable cause definition
  • what is probable cause
  • probable cause hearing

Some of the most often-researched 4th Amendment phrases:

  • 4th Amendment rights
  • what is my right to privacy?
  • what is protected by the 4th Amendment?

(You may recall the recent infographic we published, which displayed the frequency of various types of arrests in Fairfax County over a several month period. The Vincenzes Law legal team tracks all sorts of criminal law related data, and we intend to publish most findings on an ongoing basis).

To help their clients make sense of the 4th Amendment “probable cause” requirement, the protections it provides, and to answer the question, “what is probable cause,” many local Fairfax criminal lawyers and Virginia criminal attorneys discuss these three initial inquiries before going into further detail:

  1. What exactly does the U.S. Constitution tell us? (hint: not much)
  2. What does probable cause mean in the real world?
  3. What is the “probable cause” rule or test?

How does the Constitution Define Probable Cause?

The Constitution does not define probable cause. Surprised? Here is the relevant portion of the 4th Amendment:

“The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue,but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.”

This paragraph (above) has prompted decades of jurisprudence, interpretation by the courts, and application to real-life scenarios. Nothing is 100% settled. A decade from now, there may be new ways by which lawyers must analyze cases involving specific probable cause issues. While many possible questions can relate to probable cause, here are a few of the most common pretrial issues raised in an effort to suppress (or exclude) evidence:

  • What is an unreasonable search?
  • What factors give a police officer probable cause to arrest or search someone with no warrant?
  • If no probable cause exists, then what?

What Does Probable Cause Mean?

When it comes to the application of the Constitution’s 4th Amendment protections, as a Virginia criminal attorney who talks to clients and potential clients nearly every day about case-facts, I realize that many people simply want to know the answer to the basic question, “what does probable cause really refer to, in real-life?”

In the most general sense, probable cause is the the standard we hold law enforcement officials to when a warrant is sought, but this is truly only the tip of the iceberg. Federal, Virginia, and local Northern Virginia and Fairfax criminal defense attorneys must be able to spot issues ranging from the widely accepted exceptions to the warrant requirement, to the more obscure rulings on particular factual scenarios.

If you have ever served on a grand jury, then you know probable cause is also the standard used to determine whether or not a person should be indicted and formally charged with committing a criminal offense. Virginia felonies often involve a grand jury indictment, but typically misdemeanors do not.

There is No Single Rule for Determining “Probable Cause”

Like so many things in life, probable cause analysis is not black and white. The Supreme Court decided against creating a bright-line rule. As a result, judges and juries often have to take into consideration important facts as presented by the prosecution and defense. When referring to probable cause, the term we criminal defense attorneys use (perhaps) the most often:

Totality of the Circumstances

“Totality of the Circumstances” means exactly that: there is no rigid test to determine whether or not a law enforcement official or magistrate had probable cause to search, issue a warrant, or make an arrest…instead, all of the relevant facts must be considered. There are specific rules, however, when certain issues are raised. For example, a search warrant must specifically state the premises to be searched, and the items sought.

Another example I often have cited to pertaining to 4th Amendment issues and probable cause: in the context of a magistrate and a probable cause determination based on an informants tip, the Court said:

“The rigid “two-pronged test” under [2 previous cases] for determining whether an informant’s tip establishes probable cause for issuance of a warrant is abandoned, and the “totality of the circumstances” approach that traditionally has informed probable-cause determinations is substituted in its place.”
Illinois v. Gates, 462 U.S. 213, 103 S.Ct. 2317, 76 L.Ed.2d 527 (1982)

Although there is no bright-line test in general, there are cases in the past that have been decided one way or another, and all Virginia criminal lawyers and local Fairfax criminal attorneys who I regularly talk to understand that it is our job is to argue for our client after analyzing the unique facts, and after comparing their facts to other cases. Since every case is unique, it is not uncommon for one case to require an analysis of hundreds of prior cases (because certain cases can only be used for specific facts, and since each unique case usually contains dozens (if not hundreds) of unique facts, a sound defense usually requires knowledge and understanding of at least a dozen, if not 100 or more cases.

Further complicating matters is the fact that when a case’s proposition or holding is overruled, such a case is no longer considered viable (for the proposition it stood for). According to our firm and my own opinion as a Northern Virginia defense attorney and Fairfax criminal lawyer, it may still be wise to reference such a case. Why? Sometimes I like to point out a previously widely-used analysis differs from the actual, current proper approach. This is just one reason why it is important for all criminal lawyers in Virginia, federal practice, and all other jurisdictions remain up-to-date and current with the jurisprudence of not only the Supreme Court of the United States, but the Supreme Court of Virginia (or their jurisdiction’s Supreme Court), the Court of Appeals in Virginia, and the Federal Circuit Courts, among others.

Additionally, sometimes specific factual circumstances are so unique that there may be no Supreme Court or Virginia case on-point. In such a case, it requires even more research into other state or federal courts (sometimes referred to as non-binding authority, which means the court may find the other jurisdiction’s ruling persuasive but not mandatory). Mandatory authority is a rule that must be followed; the United States Supreme Court’s rulings are considered to be mandatory authority.

Future blog posts will discuss specific 4th Amendment issues, such as search and seizure; motions to suppress; warrantless searches; rules pertaining to the use of illegally obtained evidence, and more. This post is meant to simply introduce a term used repeatedly by the courts, lawyers, and scholars.

For a discussion in-person or by phone about the specifics of your case, request a consultation. It will not cost you anything. As a Fairfax criminal defense attorney serving people in Fairfax County, Prince William, Arlington, Alexandria, Falls Church, Herndon, Vienna, Manassas, and so many other jurisdictions in Northern Virginia, I know how important it is for people to talk to someone who knows the law and who is willing to take a few minutes to calm nerves and worries. To accomplish this and ease these burdens, I gladly can explain a worst case scenario, a best case scenario, and offer my professional opinion. Knowledge is power.

To reach a Virginia criminal lawyer by phone:

Do you prefer local numbers?

Dial: 703.665.3719

…or, would you rather call our toll-free line?

Dial: (1) 888.695.6565

Many local Fairfax criminal lawyers have internet-based contact forms. The Vincenzes Law Firm’s office is in Fairfax, but we serve Northern Virginia

If contacting us online is your preference:

Simply visit our contact page and submit your inquiry.

A legal professional will reply within 1-2 business days.

The following two tabs change content below.
Brenton D. Vincenzes is a lifelong Fairfax County resident and Fairfax Criminal Defense Lawyer. He is a member of the Virginia Association of Criminal Defense Lawyers, National College of DUI Defense, NORML, and has been awarded the following in 2014-15: Top 100 Trial Lawyer (National Trial Lawyers) Top 40 Under 40 Trial Lawyer (National Trial Lawyers) Nationally Ranked Top 10 Under 40 Defense Attorney (National Academy of Criminal Defense Attorneys) 10 Best in Client Satisfaction for Criminal Defense (American Institute of Criminal Law Attorneys) Nationally Ranked Top 1% Attorney Award Recipient (National Association of Distinguished Counsel) As a local leader, Mr. Vincenzes mentors troubled youths, volunteers his time to serve at his church, takes select pro bono clients, and strives to improve the community. Mr. Vincenzes represents men, women, and juveniles through zealous and diligent advocacy, strategic planning, and skilled trial work preparation. Mr. Vincenzes' areas of criminal law practice are broad, and include most felonies and misdemeanors such as: reckless driving, DUI & DWI, drug offenses, assault and battery, domestic violence, assault on an officer, destruction of property, alcohol offenses, firearm offenses, larceny, shoplifting, embezzlement, fraud, and other theft offenses, and moving traffic violations among others. His private legal services are available in most Northern Virginia jurisdictions, including Fairfax County, Arlington County, Prince William County, Loudoun County, Stafford County, Alexandria, Manassas, Leesburg, South Riding, and other cities and towns.



  1. You definitely know what you’re talking about

  2. Hi there, just became alert to your blog through Google, and found that
    it’s really informative.

    Many people will be benefited from your writing.

Speak Your Mind