Under state and federal criminal laws, an illegal search is one made by police without a search warrant and/or with unreasonable suspicion. The 4th Amendment of the U.S. Constitution protects citizens from unreasonable searches and seizures of property. In order to lawfully search a person’s body or their property, police need to have probable cause.

What is Probable Cause?

Probable cause is a reasonable belief that an individual will commit or has committed a crime or other violation. Without establishing probable cause first, any criminal search of the person’s body, belongings, or property will be deemed unreasonable and will most likely be unusable in convicting the defendant. For a reasonable belief to exist, there must be factual evidence to support the suspicion, not simply a hunch or “gut feeling.”

A common example of how probable cause works is in situations where a police officer decides to pull someone over on the highway. If the driver is swerving, speeding, braking suddenly, or driving erratically, it may be sufficient evidence to cause the police officer to have probable cause that the person is driving while under the influence. The police can then pull over the suspect based on their swerving, which provides probable cause for the stop. 

However, suppose for instance that the driver is driving normally and obeying all traffic rules. Here, the police might not be able to pull the person over for drunk driving, as they have no probable cause to believe that the person is driving while drunk. 

How is Probable Cause Established?

A police officer or other authority figure can establish probable cause in multiple ways, including:

  • The police officer’s observations, including sights, sounds, and smells (a common example of this is when a police officer smells burning marjiuana coming from a building or car); 
  • The police officer’s training or expertise which helps them identify gestures, movements, tools, preparation indicating criminal activity (some officers may have specialized training in this area);
  • Circumstantial evidence;
  • Information from informants, witnesses, and victims, especially statements regarding a suspect’s activity. 

What are the Elements Needed to Determine Probable Cause?

Probable cause is the basic standard used to determine if a crime has occurred or is occurring. In order to sufficiently establish probable cause, police need the following elements:

  • Validity of knowledge, which means that the knowledge is accurate; and
  • Reliability of knowledge.

So, for instance, suppose that the police receive a tip from a credible informant source about a robbery that is about to happen. Suppose that the informant can provide an audio recording of the persons involved planning out the robbery. This might be sufficient evidence to establish probable cause regarding the robbery. 

In contrast, if the police receive information about a robbery from a source that is not credible or that can’t be verified as accurate, then it might not be enough to establish probable cause to launch an investigation. An example of this might be information coming from an old website, with no way to verify where the information came from or who posted it. Such information might not be considered reliable enough to establish probable cause.  

Also, anonymous tips may be helpful, but often they are not enough. Rumors alone cannot be enough for probable cause, let alone a search warrant, even if they do give results. If an anonymous tip said that there was illegal drug activity within a home, but there was no other evidence to show that this was true and no way to verify the truthfulness of the rumor, then it would most likely be unusable. Even if a search did lead to evidence of illegal drug activity.

Can Police Use Probable Cause to Obtain a Warrant?

Yes. A judge must often sign an order for a search warrant in connection with a crime. In most cases, a judge will only authorize police to search a person or property after determining if there is enough probable cause to do so. 

This may create additional steps that might make the investigation take longer. However, such steps are necessary to protect the privacy rights and constitutional rights of the potential suspects involved. 

Is Probable Cause the Same as “Beyond a Reasonable Doubt”?

No, the two are related and often interact but they are not the same. Generally speaking, police need probable cause in order to conduct a search. However, once a case goes to trial, the defendant must be proven guilty “beyond a reasonable doubt”. This is the level of proof required to show that the defendant is indeed guilty. This is a fairly high standard to meet, and is instituted to help protect criminal defendants. 

Thus, to make it clear: “probable cause” is the level of suspicion needed before police can conduct a search or investigation. In contrast, “beyond a reasonable doubt” is the level of proof needed in criminal trials to find a defendant guilty. 

The level of proof in a civil case is lower than that of a criminal case. In a civil lawsuit (such as in an injury case), the court only needs to prove liability based on a “preponderance of the evidence”. This means that the court must only show that there is a greater than 50% chance that the defendant is liable based on the evidence presented in court. 

This is why a person who is found guilty in a criminal court of law will likely be found liable in a civil court of law for related issues, since the standard of proof is higher in a criminal case than in a civil lawsuit.

Should I Contact a Lawyer if I’m Facing Issues Involving Probable Cause?

Law enforcement officials may have probable cause to make an arrest or search property. However, that does not mean you are guilty of a crime; they would then need to prove guilt in court beyond a reasonable doubt. 

To understand more about probable cause and other criminal issues, and how to defend yourself in a criminal case, you may need to contact a criminal defense attorney in your area. Your attorney can inform you of your legal rights and can provide representation in the event of a criminal trial.