After graduating in '39, Allen went to MIT. During WWII he worked on a classified project headed by an MIT professor on one of the first "smart" weapons, an acoustic homing torpedo. After the war, he went to University of Virginia law school. He spent his legal career as a patent litigator, and was one of the first patent lawyers inducted into the American College of Trial Lawyers. Allen played an instrumental role in identifying the inventor of the electronic digital computer, which is written of in several histories on the subject.