[steve86]

If someone has a wi-fi server without a password protection, then I believe it is safe to assume that he is simply inviting the public to use it.

Tell it to the judge.

[pray4liberty]

If someone has a wi-fi server without a password protection, then I believe it is safe to assume that he is simply inviting the public to use it.

Not exactly. There's a difference between 'invitation' and 'tacit permission.' I believe leaving a network unsecured (which some do) falls into the latter category.