Here's the most comprehensive source of case law covering the subject I've ever seen: Computer Crime and Intellectual Property Section (CCIPS) Searching and Seizing Computers and Obtaining Electronic Evidence in Criminal Investigations "This publication provides a comprehensive guide to the legal issues that arise when federal law enforcement agents search and seize computers and obtain electronic evidence in criminal investigations. The topics covered include the application of the Fourth Amendment to computers and the Internet, the Electronic Communications Privacy Act, workplace privacy, the law of electronic surveillance, and evidentiary issues. This publication supersedes "Federal Guidelines for Searching and Seizing Computers" (1994), as well as the Guidelines' 1997 and 1999 Supplements." http://www.usdoj.gov/criminal/cybercrime/searching.html