You can't void copyright - the owner of the data still owns it, no matter how they release it. Even for a work that you put in the public domain, you still own

You can't void copyright - the owner of the data still owns it, no matter how they release it. Even for a work that you put in the public domain, you still own the copyright to it - you're simply giving everybody an unrestricted license to use it. By putting data on a publicly available website (or webservice) you are not giving up any copyright protections. It sounds like in this case the copyright belongs to the owner of the API you are querying. They are licensing their data to the consumers of their API, under the terms of service on that API. if you violate their TOS, you're violating their copyright.