Mark,
Not sure but are you an attorney or offer another kind of service to your photographer client? The reason I ask is my company is looking into a similar question regarding trademark infringement. Just so happens that I saw a post this morning here on GG regarding a local (to Atlanta) attorney who specializes in just such issues. Her name is Carolyn Wright and her website is
here. I couldn't find the posting when I was looking it up for you but I could have sworn it was from a certain well know photographer in Marina del Rey,CA. In any case, if you are not an attorney - or even if you are - maybe she can help.
Doug