Section 109 of U.S. Copyright Code (First Sale Doctrine) allows libraries and archives to borrow and lend returnable materials they have purchased ( e.g. Books, Theses, Dissertations, DVDs, CDs, etc.) through Interlibrary Loan. Section 108 allows libraries and archives to reproduce and distribute certain copyrighted works without permission on a limited basis for the purposes of preservation, replacement, and research. Section 108 sets forth some conditions that libraries and archives must meet in order to take advantage of the exceptions. Copies may not be for direct or indirect commercial advantage and the collections of an eligible institution must be open to the public or to unaffiliated researchers in a specialized field. Moreover, all copies must include either the copyright notice that appeared on the source work, or, in absence of such a notice, a statement that the work may be protected by copyright.
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For non-returnable materials (copies of articles from periodicals) a simple guideline is recommended which is called the Rule of Five.
Rule of Five: "No more than five copies of articles, chapters or other small portions of a non-periodical work may be received by a library in a given calendar year, during the entire period of copyright of the book. Starting with the sixth copy, copyright permission and royalty fees may be required. You must evaluate whether the copies requested would substitute for the purchase of the book." (from Copyright Clearance Center)
There are other guidelines and rules that need to be followed in Interlibrary loan, both by the borrowing and lending libraries. To get a better understanding of this subject please watch the video.
IF you want more information on Interlibrary Loan at Cuesta College library, read the Interlibrary Loan lib-guide that is specifically made for that topic.