Frankly it alles down to testimony. If someone can testify that yes that document was authorized it will be valid. If someone testifies that no I never intended for it to be signed then that brings up a question. It not significantly different from authenticating a wet signature which can be forged - but forgery is simply *way* easier in today electronic age. And yes as an attorney the easy acceptance of electronic documents though certainly handy has been troubling to me for years.