Final answer:
Copyright clearance is not required if the material is without licensing information, in the case of works made for hire, or if the work is in the public domain.
Step-by-step explanation:
Copyright clearance does not need to be requested in certain circumstances when dealing with copyrighted materials. One such circumstance is if the art or material appears without licensing information, it can be assumed that there are no known restrictions. However, if someone claims copyright, contact should be made to the specified copyright owner.
Another circumstance where copyright clearance is not necessary is works made for hire. In this case, the copyright owner is the party that commissioned the work, not the creator. Whether a work is made for hire is determined by the facts at the time the work is created.
Lastly, works that are in the public domain do not require copyright clearance. Anyone can copy, distribute, and make use of public domain works without seeking permission or paying royalties, although they should respect trademark licenses when applicable.