SyconciousAu,
Good call. I erred. "Implied consent" is the correct terminology, not "informed consent".
It's been a while since I researched the laws for Seattle, WA. And "informing" was required. Informing could be done with a sign, or if on the phone an announcement that "This call may be recorded for quality assurance". If people proceed past the sign, or stay on the phone line, that can be construed as "consent". IIRC.
I read that WA state code you found, and read a bunch of other stuff, since the laws involved are at the state, county, and city level. I concluded the sign was adequate for people coming up my driveway (the main access)
If people creep through the woods, they won't see the sign. And yes, recording burglars could get me in trouble. Just as if they tresspass, climb a ladder, fall and get hurt - then I'm on the hook.
I do intend to put a camera on the side of my house, with audio. I will turn down the volume to not record the neighbor's voices as they get in or out of their car.
From a practical standpoint, how would someone get my audio recordings? Yes, someone could claim my sign was inadequate, if we reached that point. Yes, the very "act" of recording is what we're discussing here, in terms of legality. Recording, and then using that recorded audio, seems that's where the trouble would appear. I don't mean to sound like a "jail house lawyer" (I'm an engineer, not in the legal industry). I may be bending the law, but I wouldn't turn over the audio to anyone.
When I'm away from home, and someone bad approached my front door, I'd like audio for my own personal and private use. I may be tilting at windmills, but listening to people who intend to maybe do bad things seems more righteous and noble than protecting the miscreants from being recorded without their consent. After all, they entered my property despite the "no trespassing" signs.
Thanks for the thoughtful response, it's appreciated. Tricky subject of audio recording.
Fastb