Try explaining computer science to a young child sometime. That task might be easy compared with attempting to educate the participants of a courtroom proceeding. Reading through the transcripts of the trial in which I was involved, I noticed some confusion concerning the legality of port scanning. A port scan is analogous to a person walking down the street and checking for open doors and windows. Factors such as those take center stage when the prosecution relies largely on circumstantial evidence.
Evidence is defined as direct proof of a fact.
Jurors are asked to use common sense in evaluating evidence. Fortunately, the prosecutor's common sense and experience kept this ridiculous case from going to trial. The average person's knowledge of computer science likens to an 18th-century farmer's knowledge of physics. My case involved more than 100 pages of testimony describing how an intruder entered a trusted machine via FTP, brought over a sniffer package, failed to compile it, and then removed a critical database file. No direct evidence showing the attacker's identity, just an account of the events.