The lathe that killed Yale student Michele Dufault ’11 last April, which had no guards and no emergency stop button, would not pass muster under the university’s strict new safety rules. And the shop where Dufault died alone—which, under the new rules, is deemed one of the most hazardous on campus—is no longer accessible to undergraduates without a faculty or staff supervisor. Those are two of the most significant changes under the new safety standards, which Yale put in place this summer in the wake of Dufault’s death. The 22-year-old physics and astronomy major from Scituate, Massachusetts, was asphyxiated after...