Writing for the majority in Carpenter v. United States, Chief Justice John Roberts called the court’s momentous Fourth Amendment decision “a narrow one.” The specific holding—that a warrant is required for law enforcement to access historical cell site location information (CSLI)—may indeed be narrow, and the decision rightfully cautions that “the Court must tread carefully” when considering new technologies.

The Supreme Court’s recent decision in Carpenter v. United States raises lots of fascinating and novel Fourth Amendment questions. In this post I want to focus on one interesting and important set of questions: When does a Carpenter search start, and when does it stop? I don’t have a lot of answers, but I think the questions are important to consider. This post will explore the questions and will end with a set of hypotheticals that I think are worth pondering.

The Supreme Court’s decision in Carpenter v. United States has lots of new directions in it. One direction that some commentators have focused on is its impact on the law of subpoenas.

The Supreme Court has handed down its long-awaited decision in Carpenter v. United States. The opinion is only an hour old as I start to write this, but I wanted to offer some initial thoughts that I will also cross-post at The Volokh Conspiracy.

I'll do it in the form of a question-and-answer session, asking questions you may have and offering answers as best I can. Also, rather than wait to the end and post all of my thoughts at once, I will add to this post throughout the day.