According to the New York Times, the Syracuse faculty voted to give Biden an “F” grade after he ”used five pages from a published law review article [Comment, Tortious Act as a Basis for Jurisdiction in
products Liability Cases, 33 Fordham L. Rev. 671 (1965)] without quotation or attribution” in his 15-page paper for his legal research and writing course.
Biden was permitted to re-take the course the following year, and he “received a grade of 80 in the course, which, he joked today, prevented him from falling even further in his class rank. Mr. Biden, who graduated from the law school in 1968, was 76th in a class of 85.”
So when Trump calls him “low I-Q,” he probably is remembering that story. (Although the cheating is more a question of low-ethical-sensitivity, to put it in kindest words available).