The White House has made a house of cards out of the public bathroom issue by nominating self gender identification as the criterion for gender bathroom use.
Any state law or local law or local ordinance on this matter should have physical characteristics surrounding the matter that are readily identifiable to any ordinary prudent person.
Under the circumstances not even the (North Carolina legislature) birth certificate test would be possible at the time of the public bathroom use by the transgender person unless it is unreasonably assumed that birth certificates must be on the individual person at the time of facility use. Consequently there should be some other test which is readily available to all persons who are involved in the immediate situation in which the restroom is used. Based on this assumption the transgender person should have the physical appearance of the sexually identified gender – he or she must have the physical characteristics of his or her gender identification. In this manner facts and circumstances could be merged by all parties present. To me the physical characteristics test including the manner of dress should be particularly important in constructing any law or ordinance which is for the convenience of the transgender person and those with whom that person interacts in the immediate circumstances.
For example, the physical features of the transgender person which obviously belong to one gender or another depending on the circumstances, as well as the selection of clothes customarily male or female in nature, would be determinative of the gender identification in question. In other words the old saying “if it walks like a duck and talks like a duck it’s a duck”would govern.