Probable Cause

Question 1

Draper v. United States (informant’s tip, which was corroborated with an accurate, predictive description)

Answer 1

Probable cause exists where the known facts and circumstances would cause a reasonable person to believe that an offense had been, or is being, committed.

Question 2

Aguilar v. Texas (warrant was issued based on the officers’ affidavit, which stated that they had received reliable information from a credible person that narcotics could be found in defendant’s home.)

Answer 2

Proposal for an arrest warrant must contain an affirmative allegation that the affiant or the affiant’s unidentified source spoke with personal knowledge of the matters contained therein.

Question 3

Illinois v. Gates (The police received an anonymous letter outlining specific details about the Defendants, Gates and others (the “defendants”), plans to traffic drugs from Florida to Illinois. When the details were corroborated by the defendants’ actions, police obtained a search warrant and found drugs, weapons and other contraband in the defendants’ home and automobile.)

Answer 3

Where an anonymous tip is corroborated with actual police findings, a “totality of the circumstances” approach is an appropriate way of determining probable cause instead of using the two-pronged test of “veracity/reliability” and “basis of knowledge” from Spinelli v. United States, 393 U.S. 410 (1969). The Fourth Amendment of the United States Constitution (”Constitution”) requires no more than a finding by an issuing magistrate that there is a “substantial basis” that a search will uncover evidence of wrongdoing.

Question 4

Florida v. Harris (The dog signaled that there was a suspicious odor on the driver-side door’s handle. Taking that as sufficient reason for a search, the officer checked out the interior of the vehicle, turning up materials known to police as the ingredients for making methamphetamine.)

Answer 4

When, subject to challenge by the defendant, the police provide evidence of a drug-sniffing dog’s satisfactory performance in a certification or training program, the dog’s alert can provide probable cause to search a vehicle.

Question 5

Commonwealth v. Dunlap (The officer testified that he saw Dunlap exchange several “small objects” for money. The officer said that in view of his training and experience and the nature of the neighborhood, he believed that he witnessed a drug transaction.)

Answer 5

The court held that this did not amount to probable cause. The U.S. Supreme Court denied cert.

Question 6

Probable cause exists when:

Answer 6

The Facts and circumstances within an officer’s personal knowledge and about which s/he has reasonably trustworthy information, are sufficient to warrant a “person of reasonable caution: to believe that: (1) in the case of an arrest, an offense has been committed and the person to be arrested committed it, or (2) in the case of a search warrant, an item described with particularity will be found in the place to be searched.