NO UNLAWFUL OR PROHIBITED USE. As a condition of your use of the Services, you will not use the Services for any purpose that is unlawful or prohibited by these terms, conditions, and notices. You may not use the Services in any manner that could damage, disable, overburden, or impair any Flickr server, or the network(s) connected to any Flickr server, or interfere with any other party's use.
If you use someone else's copyrighted materials without permission, that use generally violates the copyright owner's exclusive rights, and is copyright infringement. So if you create a new work and include parts of other people's works in it (such as an existing photo), you must own or have permission to use the elements you borrow. For example, if your project is based on an existing popular series, you should obtain permission to use the elements you borrow from the series.