MBE Rules · Criminal Procedure
Cell-Site Location Data
Carpenter v. United States
The rule
Obtaining seven or more days of historical cell-site location information is a search requiring a warrant; the third-party doctrine does not extend to the comprehensive record of physical movements.
In plain English
Under the law, accessing seven or more days of historical cell-site location data is considered a search that requires a warrant. This is because such data reveals a person's detailed physical movements over time, which goes beyond what a person voluntarily shares with third parties.
Worked example
Police obtained a warrant to access a suspect's cell-site location data for the past two weeks, revealing that he was near the scene of a crime during the time it occurred. The court upheld the warrant as valid, emphasizing that the extensive tracking of the suspect's movements constituted a search.
Memory hook
Seven days of cell data = warrant needed!
The trap
Exams may present scenarios where students mistakenly believe that any cell-site data can be accessed without a warrant, ignoring the specific threshold of seven days.
How examiners test it
Questions often involve fact patterns where law enforcement seeks to obtain cell-site data, testing whether students recognize the need for a warrant based on the duration of the data requested.
Drill this rule until it can't fail you.
Vrenberg generates unlimited questions on this exact rule, tracks your mastery of it, and brings it back until it sticks.