How long is too long for a traffic stop?

Wait A Second! today reminds us that traffic stops can violate the Fourth Amendment's reasonableness requirement. In this post, the blog highlights the recent Second U.S. Circuit Court of Appeals decision holding that a half hour stop was not unreasonable under these circumstances:

The case is Harwe v. Floyd, a summary order decided on October 17. The stop lasted a half hour. Floyd stopped Levy's car because she swerved without signaling. She admitted drinking alcohol at dinner. The Second Circuit (Raggi, Droney and Keenan [D.J.]) says that Floyd reasonably continued the stop "beyond the time necessary to issue a traffic violation in order to assuage reasonable suspicions as to driver sobriety." He necessarily questioned Levy and Harwe separately because Levy failed two sobriety tests, further lengthening the stop.

The case seems simple enough, but nothing under the Fourth Amendment is simple. Levy says the officer should have instead investigated her claim that she failed the sobriety tests because she was a stroke victim. But the Court says that Floyd's interview at the time was reasonable. The plaintiffs also argue that Floyd wasted time talking with other officers "who purported laughed and pointed at Levy." But even if this conversation was unrelated to the stop, it was relatively brief in comparison to the necessarily more time-consuming sobriety tests, preliminary questioning, the placement of Levy in the police car and filling out the citation, among other things.