Larry Craig and restroom etiquette

This week the ACLU decided to stick their oar in regarding the vexed question of whether Larry Craig should have been prosecuted for soliciting gay sex in a restroom stall in Minneapolis Airport. Their logic was interesting. There is apparently case law in Minnesota to say that one has an expectation of privacy when in a bathroom stall, even if the stall is in a public place. Therefore, the ACLU argue, it is entirely legal to have gay sex in the stall of a public toilet in Minnesota, since you’re doing it in private.