In March 1976, plaintiff Albin Laaperi purchased a smoke detector from Sears. The detector, manufactured by the Pittway Corporation, was designed to be powered by AC (electrical) current. Laaperi installed the detector himself in one of the two upstairs bedrooms in his home. Early in the morning of December 27, 1976, a fire broke out in the Laaperi home. The three boys in one of the upstairs bedrooms were killed in the blaze. Laaperi's 13-year-old daughter Janet, who was sleeping in the other upstairs bedroom, received burns over 12 percent of her body and was hospitalized for three weeks. The uncontroverted testimony at trial was that the smoke detector did not sound an alarm on the night of the fire. The cause of the fire was later found to be a short circuit in an electrical cord that was located in a cedar closet in the boys' bedroom. The Laaperi home had two separate electrical circuits in the upstairs bedrooms: one which provided electricity to the outlets and one which powered the lighting fixtures. The smoke detector had been connected to the outlet circuit, which was the circuit that shorted and cut off. Because the circuit was shorted, the AC-operated smoke detector received no power on the night of the fire. Therefore, although the detector itself was in no sense defective (indeed, after the fire the charred detector was tested and found to be operable), no alarm sounded. Laaperi brought this diversity action against defendants Sears and Pittway, asserting negligent design, negligent manufacture, breach of warranty, and negligent failure to warn of inherent dangers. The parties agreed that the applicable law is that of Massachusetts. Before the claims went to the jury, verdicts were directed in favor of defendants on all theories of liability other than failure to warn.... Laaperi's claim under the failure to warn theory was that he was unaware of the danger that the very short circuit which might ignite a fire in his home could, at the same time, incapacitate the smoke detector. He contended that had he been warned of this danger, he would have purchased a batterypowered smoke detector as a back-up or taken some other precaution, such as wiring the detector to a circuit of its own, in order better to protect his family in the event of an electrical fire. The jury returned verdicts in favor of Laaperi in all four actions on the failure to warn claim. The defendants' motions for directed verdict and judgment notwithstanding the verdict were denied, and defendants appealed. The Court affirmed the judgment in favor of Albin Laaperi in his capacity as administrator of the estates of his three sons. In the action on behalf of Janet laaperi, the verdict of the jury was set aside, the judgment of the district court was vacated, and the cause was remanded to the district court for a new trial limited to the issue of damages.

1. This a US Court of Appeals case from the First Circuit in Massachusetts. Why is this case in federal court?
2. Why does the court talk about its "sense of the current state of tort law in Massachusetts" and how this case "would be treated by the Massachusetts courts," as if it were not in the state at all but somehow outside?
3. What rule of law is in play here as to the defendants' liability?
4. This is a tragic casethree boys died in a house fire. Speaking dispassionatelyif not heartlesslythough, did the fire actually cost Mr. Laaperi, or did he lose $3.4 million (in 2010 dollars) as the result of his sons' deaths? Does it make sense that he should become a millionaire as a result? Who ends up paying this amount? (The lawyers' fees probably took about half.)
5. Is it likely that smoke-alarm manufactures and sellers changed the instructions as a result of this case?