re: #238 Absalom, Absalom, Obdicut

Somewhat, not exhaustive. I found this though. I confess I am leaning on the work of the legal people at the ACLU.

USA PATRIOT Act

Section 216 of the 2001 USA PATRIOT Act expanded the definition of a pen register to include devices or programs that provide an analogous function with internet communications. Prior to the Patriot Act, it was unclear whether or not the definition of a pen register, which included very specific telephone terminology, could apply to internet communications. Most courts and law enforcement personnel operated under the assumption that it did, however the Clinton administration had begun to work on legislation to make that clear, and one magistrate judge in California did rule that the language was too telephone-specific to apply to Internet surveillance.