Answer: Carpenter v. United States
Step-by-step explanation:
In her interview with C-Span, Sarah Brayne referenced the Carpenter v. United States case which related to a case where federal investigators were able to arrest Timothy Carpenter for theft by tracking the location of cell phones.
The Supreme Court ruled that the this was a violation of the Fourth Amendment and that the government needed to get a warrant before they would be granted access to phone number locations moving forward.