By U.S. copyright law, a person may use copyrighted material in their own work if that use satisfies the Four Factors of Fair Use. This generally protects educators and critics who need to reference copyrighted material in the course of their work.
The Four Factors are (taken from the source linked above):
1. the purpose and character of the use, including whether such use is of a commercial nature or is for nonprofit educational purposes;
2. the nature of the copyrighted work;
3. the amount and substantiality of the portion used in relation to the copyrighted work as a whole; and
4. the effect of the use upon the potential market for or value of the copyrighted work.
For example, I decided to write a “Whom to Follow” piece an a journalist named Jeremy Scahill. As a part of the piece, I included a clip from a recent podcast that he hosts. The piece that I wrote is educational—an assignment for a class that I am sharing with my classmates (and the public)—and contextualizes the clip and is not for profit, so it passes the first factor. The clip that I included is an interview. In as much as it is journalism, it is factual; but I included the clip not so much to communicate the content of the interview as to point to the interview itself and that the interviewer cared to share it, so I would regard the work not as a factual in nature, but as a creative work. I included it to demonstrate the nature of the author’s creativity, so I believe it passes the second factor. The clip that I included is about 15 minutes out of a 57-minute episode. While that meets the legal definition of substantial, it is one story and not the main story of the episode; and as a representation of the whole series, it is not substantial. I believe that it passes the third factor. Since the copyrighted work is a podcast that can be legally downloaded for free from multiple platforms, and I link to one of them, I am definitely not negatively affecting the market for the work, so it passes the fourth factor. This is a fair use.