Does OA violate copyright?
OA is in copyright compliance because it requires the consent of the copyright holder (unless the work is already in the public domain). The legal basis of OA is the consent of the copyright holder (for newer literature) or the expiration of copyright (for older literature). An increasingly common and easy way for copyright holders to manifest their consent to OA is to use one of the Creative Commons licenses. Many other open-content licenses will also work.