FCC regulations used to clearly state that any program that was not a live broadcast had to be clearly stated as such.
In recent years, with taped programming become predeominate, it's been reinterpreted to mean that anything that presents itself as a "live" show but isn't has to be identified that way--like "SNL" reruns on Saturday nights at 11:30 on NBC or any repeats or repurposes of live programs. In other words, if you have an announcer shouting "live!" and it isn't, you better have a "pre-recorded" graphic up somewhere anytime around that announcer shouting "live!"
At CBS, the "pre-" was dropped from "recorded" sometime in the 60s at the request of Bill Paley, who thought "pre-recorded" was redundant. He also required that news shows could only call themselves "broadcasts," not "programs" or "shows" (something "60 Minutes" continues to this day) and, less successfully, he wanted shows that used canned laughter to run disclaimers ("audience response technically augmented" disclaimers had a very short run on the CBS air after the quiz scandals, when Paley wanted to clear up everything).