The Collective Knowledge Doctrine in Federal Searches and Arrests
A police officer may sometimes stop, search, or arrest a person based on information known by another officer. This principle is called the collective knowledge doctrine. But the doctrine does not permit police to combine unrelated hunches or to use information discovered after a search to retroactively create probable cause.
When Can Police Stop a Driver for Suspected Cell Phone Use?
A police officer cannot lawfully stop a vehicle based merely on a hunch that the driver might be violating a traffic law.
A traffic stop is a seizure under the Fourth Amendment. To justify the stop, police generally must have a particularized and objective basis—reasonable suspicion—to believe that the...
Gun Suppressed After Successful Fourth Amendment Challenge
When police recover a firearm during a search, the discovery of the gun does not automatically make the search constitutional.
The Fourth Amendment requires law enforcement officers to have a lawful basis for the search or seizure that produced the evidence. If police violate the Fourth Amendment, the defense...
Can Police Stop You Based on an Anonymous Tip?
An anonymous accusation does not automatically give police authority to stop, frisk, or search someone. Officers must have specific facts supporting a reasonable suspicion that criminal activity is occurring, and the tip must contain sufficient signs of reliability.
If police stopped or searched you based on an anonymous caller...
Fourth Amendment Terry Stops and Protective Frisks
Police cannot detain and frisk someone merely because the person appears nervous, is present in an area associated with crime, or refuses to cooperate with an officer. A Terry stop requires reasonable suspicion of criminal activity, and a protective frisk requires an additional reasonable belief that the person is armed and dangerous.
Inevitable Discovery and Inventory Searches of Vehicles
Police cannot use an inventory search as a pretext to search a vehicle for evidence. The government must establish that the impoundment was lawful, that the inventory followed standardized procedures, and that the challenged evidence would inevitably have been discovered through those lawful procedures.
If police searched your vehicle...
IP Address Search Warrants in Federal Criminal Investigations
Federal investigators frequently use IP addresses to identify the internet connection associated with suspected online criminal activity. That information may then be used to obtain a search warrant for a home, computer, cell phone, or other electronic device.
But an IP address and a person are not the same...
Search Warrants and Probable Cause: When Can a Warrant Be Challenged?
A search warrant does not automatically make a government search constitutional.
Before issuing a search warrant, a judge must determine that there is probable cause to believe evidence of a crime will be found in the particular place to be searched.
That determination is ordinarily based...
Franks Hearings and False Search Warrant Affidavits
A search warrant does not protect an unlawful search when police intentionally or recklessly mislead the judge who issued it. Under Franks v. Delaware, a defendant may challenge material false statements and omissions in a warrant affidavit and seek suppression of the resulting evidence.
If police obtained a search...