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. - Fourth Amendment to the Constitution of the United StatesProbable cause is among the most important legal protections U.S. citizens have against the exercise of government power. It is provided through the 4th Amendment because governments at all levels- national, state, and local - have great resources at their disposal to monitor people's activities, search their belongings, invade their residences, and deprive them of their liberty by arresting and jailing them. Citizens rely on the 4th Amendment to protect their privacy from government intrusion and their possessions from government seizure.
While the language of the 4th Amendment focuses on issuance of search warrants, probable cause comes into play in a variety of circumstances. One of the most common is when a police officer in the field suspects someone of engaging in criminal activity and must decide if probable cause exists to make an arrest.
Different definitions of probable cause have been articulated over the years, but they boil down to this: Can a reasonable person deduce from the evidence at hand that a crime has been or is being committed. Though similar to the notion of reasonable suspicion, which pertains to brief detention and questioning by police, probable cause is a more demanding standard, requiring more evidence and greater suspicion of wrongdoing. (See the October 22 post for a discussion of reasonable suspicion)
The difference between probable cause and reasonable suspicion in questioning and arrest can be illustrated this way. Let's say there's been a robbery at a local electronics store. Police may briefly detain and question a person if he is driving a car matching the description of a vehicle seen driving away at high speed from the store at the time of the robbery. Reasonable suspicion is satisfied. But more is needed for probable cause to make an arrest. One way would be for police to verify ownership of the car. If it is not registered to the person driving it, that is a step toward meeting the standard of probable cause. It doesn't prove guilt, but it certainly heightens suspicion. Next, police might look to the behavior of the person driving the car. If that person can't explain clearly where he's been or where's he's going, probable cause is closer to being met. Police, in this example, might also see boxes of what appear to be cell phones and Blu-ray disk players in the back seat. These facts taken together would most likely be enough to satisfy the standard of probable cause and allow police to make an arrest. It doesn't mean that the suspect is guilty; it means that sufficient evidence exists for the government to begin the process of filing formal criminal charges.
Probable cause related to search warrants is quite complicated, even though the 4th Amendment seems to make a clear declaration that no searches shall be conducted without a warrant. We'll go over this in a coming post, but at this point keep in mind that police may search a person and her house without a warrant if exigent, or emergency, circumstances exist. Therefore, if a person poses a threat to public safety, police can do a pat down search to be certain that no weapons are present. Also, if a suspect is running from police and enters her apartment, police are allowed to follow her into the apartment because there's a danger that she might destroy evidence, do harm to others, or find a means of escape.
The key point to keep in mind is that each incident that calls for the application of probable cause has to be judged on its own, since each presents a unique set of facts and circumstances.
If you have questions about whether law enforcement had probable cause to arrest you or someone you know, call the Law Office of Nancy King.
