So far, the lower courts have set the precedence that IPs are not people. If I catch an IP doing something wrong, I can't yet say to the ISP account holder "Your IP did this, therefor YOU are guilty," for the very same reason red light cameras need to identify the driver of a car running the light instead of only the license plate.
If you have a locked wi-fi and are sharing files via torrent, in civil proceedings (which these are), the companies have plenty of evidence saying that you are probably the one sharing the files. Remember, it's civil: "beyond a reasonable doubt" isn't required.
And if you fail to protect your wi-fi they could claim negligence. "I have heard other lawyers compare leaving your wifi open to leaving a loaded gun lying around." (http://torrentfreak.com/are-you-guilty-if-pirates-use-your-i...).
I think it would ironic if WEP became popular again because it could protect negligence and is trivially hacked.
That's just the theory of the author of that essay. It has never been tested in court. The "judgement" the author claims at the start of his essay was actually a settlement offered by someone who thought $10000 was worth less than the risk of a court case. (Perhaps because he didn't want to be publically accused of downloading gay porn.) That whole essay is based on deception, and the author is a sleazebag.
