Apparently we’re going to get one of our first wardriving prosecutions out of the great state of Florida. I’ll be commenting on the case over at Joe Gratz’s blog. I almost had a case exactly like this under section 502 of California’s Penal Code which makes it a crime if someone:

(c)(3) knowingly and without permission uses or causes to be used computer services or (7) knowingly and without permission accesses or causes to be accessed any computer, computer system, or computer network.

The case ended up being about something else, so we never got to fully adjudicate it. But it appears that the statute covers using an open wireless access point. The only question is whether such use is with or without permission and if so, whether the defendant needs to know his use is without permission.
This is a copy of the brief I filed on whether the defendant needs to know that his wireless use is without permission in the State of California. A lot of these principles would apply to any statute, however. Download brief.