"There are three legal paradigms through which to characterize computer intrusion. These paradigms overlap each other. In addition, an intrusion can fit into any two or all three of the paradigms. These are: law enforcement, intelligence collection, and military operations. The legal challenge in any computer intrusion is properly characterizing the intruders' categorical legal identity. This will determine whether one or more of the above paradigms are applicable. Each as has strengths, weaknesses, and limitations. Each also requires that an intrusion be dealt with according to its own precise standards."
Naval Postgraduate School, Dudley Knox Library: http://www.nps.edu/Library/index.aspx