Does the use of a pen register pursuant to the Fourth Amendment, or is it controlled by a third party?

The district court held, and the government argues, that this case is controlled by Smith v. Maryland , 442 U.S. 735, 99 S.Ct. 2577, 61 L.Ed.2d 220 (1979), which helped establish the so-called third-party doctrine in Fourth Amendment jurisprudence. Smith held that the government's use of a pen register to record the numbers the defendant dialed from his home telephone did not constitute a Fourth Amendment search, because individuals have no reasonable expectation of privacy in information

[973 F.3d 990]