Dear Customer (name blocked for privacy),
While a person may state such a notice on their website, it may not necessarily prevent them from being sued for copyright violation. What it may do, however, is serve as a warning to anyone who copies or otherwise uses the material that they may guilty of violating another party's copyright. Then, if the user is accused of violating copyright law, they may not be able to claim they did not know or were innocently doing so.
As to who may own a copyright on a photo, you may be able to conduct a search on the US Copyright Office records at http://www.copyright.gov/records/ (note it is .gov NOT .com) . A search for such a record may require you to know at least the photographer or first copyright owner's name and to then, perhaps, research a trail of ownership or transfers if the original copyright was sold or assigned to another party.
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PLEASE NOTE: Responses here are for information/education only, NOT legal advice and do not form attorney-client relationship! Only licensed attorneys you hire in your state can provide legal advice.
