Mod-Search: Gallery Users need to agree to terms of use before upload

Hi!

I'm running a more or less public gallery: Users are free to register and then they can upload pictures into their albums which are shown to the public. For legal reasons here in germany this is tricky for me as the site owner: I'm responsible for the pictures my users are posting. So I need to ensure that the users got the copyrights for the pictures they put in. So I want - either after new user registering or before uploading - a dialogue which tells them the small printed legal stuff. The user then needs to agree and then he can continue. The statement that he agrees should be saved somewhere - would be perfect that way. So if some law-guys send me some dissuasion I can forward them the IP of the uploader and the agreed terms of use & legal stuff....

Anyone already developed such thing for gallery?

Thanks for any idea regarding this topic!