The legal notice is indeed annoying, and the only reason to have it there would be to have legal recourse against somebody who logs in without being authorized to do so. By clicking on it he accepts responsibility for his actions.
I have my new user sign an internal account application form that states that they have read and understood our University's Computing Ethics policy. The policy is available online and as a print-out for them. Thus, in case of problems, I just have to say 'According to Section x of the Computing Ethics Policy, which, by the way, you acknowledged in writing to have read and understood, you did ...".
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There are two types of vessels, submarines and targets.
