The ruling seems to suggest that the cease-and-desist letter was a key factor, and that it might not apply to someone who legitimately didn't know they'd been banned:
"The banned user has to follow only one, clear rule: do not access the website. The notice issue becomes limited to how clearly the website owner communicates the banning. Here, Craigslist affirmatively communicated its decision to revoke 3Taps’ access through its cease-and-desist letter and IP blocking efforts."
"The banned user has to follow only one, clear rule: do not access the website. The notice issue becomes limited to how clearly the website owner communicates the banning. Here, Craigslist affirmatively communicated its decision to revoke 3Taps’ access through its cease-and-desist letter and IP blocking efforts."