However, there may be some material that is available to the world, like news reports etc, and those who own it may not want to license it to you or you may not be able to track down the owners or it may be so costly that you can't afford to clear it but it's extremely important to the piece you are creating.
In these cases, and I want to make this very clear that this is just my opinion and I am not a lawyer, you MIGHT be able to make a case that you can use the material under fair use. According to the U.S. Copyright Office Web site,
"The doctrine of fair use has developed through a substantial number of court decisions over the years and has been codified in section 107 of the copyright law.
Section 107 contains a list of the various purposes for which the reproduction of a particular work may be considered fair, such as criticism, comment, news reporting, teaching, scholarship, and research. Section 107 also sets out four factors to be considered in determining whether or not a particular use is fair:
- The purpose and character of the use, including whether such use is of commercial nature or is for nonprofit educational purposes
- The nature of the copyrighted work
- The amount and substantiality of the portion used in relation to the copyrighted work as a whole
- The effect of the use upon the potential market for, or value of, the copyrighted work
If you are uncertain about whether something would be considered fair use or not, you can consult an attorney who specializes in fair use law and he or she can write up a fair use opinion report. You could then use that report to substantiate your use of the un-licensed material.
Also fair use attorney Michael McDonald wrote a book on the subject: Clearance & Copyright: Everything You Need to Know for Film and Television. Check it out if you want to know the gritty details about clearances and copyright. It's a fascinating topic for filmmakers.
The major downside to using un-licensed material and invoking fair use is not having access to a high resolution image for your piece - which may be the deciding factor on whether to use it or not.