Thanks for making me double check, seems you're right. The most restrictive requirement seen in courts appears to be a "reasonableness" requirement judging by

Thanks for making me double check, seems you're right. The most restrictive requirement seen in courts appears to be a "reasonableness" requirement judging by the totality of the circumstances involved: http://www.volokh.com/posts/1227548515.shtml http://www.volokh.com/posts/1227548515.shtml