opinion: Mr. Chief Justice Warren
  delivered the opinion of the Court.
  The question in this case is whether the Court of Appeals for the Eighth Circuit, under the applicable principles hereinafter discussed, properly held that it was error to submit to a jury’s determination whether an insured died as a result of suicide or accident.
  Petitioned is the beneficiary of two policies issued by respondent in 1944 and 1949 insuring the life of her now-deceased husband, William Dick. Each policy contained a clause which provided that double indemnity would be payable upon receipt of proof that the death of the insured “resulted directly, and independently of all other causes, from bodily injury effected solely through external violent and accidental means,” but that the double indemnity would not be payable if the insured’s death resulted from “self-destrúction, whether sane or insane.”
  Mr. Dick met his death while alone in the silage shed of his farm. The death resulted from two wounds caused by the discharge of his shotgun. Petitioner filed proofs of death but respondent rejected her claim for double •indemnity payments on the ground that Mr. Dick had committed suicide. Petitioner then filed suit in the North Dakota courts. Her complaint set forth the policies in issue, the facts surrounding her husband’s death, an allegation that the death was accidental, and a demand for payment. Respondent removed the case to the United States District Court for the District of North Dakota on the grounds of diversity of citizenship and jurisdictional amount. It then filed an answer to the complaint in which it set up suicide as an affirmative defense to the demand for double indemnity payments. Respondent admitted liability for the face amounts of the policies ($7,500) and no issue is presented concerning those amounts.
  Trial proceeded before the district judge and jury. The evidence showed that the Dicks, who had been happily married since 1926, lived on a farm near Lisbon, North Dakota, where they raised sheep, cattle and field crops. Five of the six quarter sections of the farm were unmort-gaged and Mr. Dick, who was not known to have any financial problems, had nearly $1,000 in the bank. He was known as a “husky,” “strong,” “jolly” man who was seldom moody. “If he had anything on his chest, he would get it off and forget about it.” Dick got along well with his neighbors and was well liked in the community. He was 47 at the time of his death. He was five feet seven inches tall, weighed approximately 165 pounds, and was generally healthy. The coroner, who was also Dick’s personal doctor, testified that Dick was a mature, muscular, physically able workman who, three weeks before his death, was bright and cheerful. About a year and a half before his death, Mr. Dick visited the doctor and complained that he felt tired and pepless. His condition was diagnosed as mild to moderate non-specific prostatitis for which he received sulfa treatments and hormone shots. But the record is devoid of evidence that the condition was serious or particularly painful or that Mr. Dick was especially concerned with it. The Dicks reared five children. One daughter still lived with them and attended high school in nearby Elliott. Dick got along well with his whole family.
  The evening before he died, the family returned from Elliott and ate ice cream and watched television together. Mr. Dick helped his daughter with a school problem in general science explaining to her the intricacies of a transformer. He slept soundly that night. He intended to help his cousin — a neighbor — make sausage the following day. He arose the next morning, milked the cows, ate a hearty breakfast, and spoke with his wife about their plans for the day. He said nothing to indicate that he contemplated doing anything out of the ordinary. About 8:30 a. m., Mrs. Dick drove their daughter to school. Mr. Dick backed the car out of the garage for his wife and said goodbye in a normal way.. He was then in the process of feeding milk to the pigs and silage-to the'cattle.'
  Mrs. Dick returned in about a half hour and proceeded' to work, in the house. Later, when she thought it was time to leave .-for the cousin’s house, she went to .locate Mr. Dick.' She walked to the barn and called for fiim but there was no answer. She then went to the little 8 foot by 12 foot silage shed adjacent to the barn and saw Mr. Dick lying on the floor. He was fiflly clothed for the zero weather Lisbon was then experiencing and he wore bulky gloves and a heavy janket which was fully zipped up. Near him lay his shotgun. A good part of his head appeared blown off and she knew from his appearance that he was dead, ’^he hurriedly returned to the house and called Mr. Dick’s brother who lived nearby. He came immediately and at Mrs. Dick’s direction went to the silage shed. There he saw Mr. Dick lying with his head to the northwest and his feet to the Southeast of the shed. The body was along the south wall with the feet near, the corner. Later, when he examined the shed more closely, he found a concentration of- shotgun pellets high 'in the northwest corner of the shed and other pellets four to five feet from the floor in the southeast corner. He also noticed a sprinkle of frozen silage on the floor of the shed and on the stepsTeading to the door from the shed.
  James Dick, the deceased’s nephew, also Responded to Mrs. Dick’s calí. He stated that upon arriving at the' Dicks’ house, he saw a tub newly filled with ground corn in the silage yard and that normally his uncle fed silage with a topping of ground corn to the cattle. He also stated that the cattle were just then finishing the silage presumably laid out by Mr. Dick before his death.
  At about 11 a. m., the sheriff arrived. .Mr. Dick was still lying where he had died. The sheriff examined Mr. Dick’s shotgun and found two discharged shells in its chamber. The gun was dry and clean and there were no bloodstains on it or on the gloves which Dick was still wearing. The sheriff also noticed some of the shot patterns found by Dick’s brother and saw some brain tissue splattered on the southeast corner. He found a screwdriver lying on the floor about a foot from the gun. The Dicks used the screwdriver to open and close the door to the silage shed because the doorknob was missing.
  Soon thereafter the coroner arrived. He testified that Mr. Dick’s body contained a shotgun- wound on the left side and one bn the head. The body wound was mortal, but not immediately fatal. It consisted of a gouged out wound on the left lateral chest wall which removed skin, fat, rib muscles and portions of rib from the body.' In addition, other ribs were fractured and Dick’s left lung was collapsed.' In the coroner’s opinion, it was the type of wound which would have had to result in immense pain, although it probably would not have made it impossible for Dick again to discharge the gun. The wound to. the head caused immediate death. According to the testimony of the sheriff and a member of the Fargo police department, both wounds were received from the front. In the sheriff’s opinion, the chest wound was received from an upward shot into Dick’s body, but this testimony conflicted with another statement of the sheriff indicating-that the wound was received from a downward shot.
  It was clear from the testimony that Mr. Dick was an experienced hunter. Petitioner testified that he kept the shotgun in the barn because of attacks on his sheep by vicious dogs during the preceding year. A number of the sheep had been killed in this manner. In addition, Dick had mentioned seeing foxes near the barn. Mrs. Dick testified that when, her husband went hunting, he sometimes borrowed his father’s gun because he didn’t trust his own. She was with him once when the gun wouldn’t fire and.had been told that occasionally it fired accidentally. .In addition, Dick’s brother testified that while hunting with Dick he heard a shot at an unexpected time which Dick explained as hn accidental discharge that occurred “once in a while.” The gun was over 26 years old.
  The sheriff testified that after the death'he tested Dick’s gun by cocking and dropping it a number of times. The triggers did not release on any of these occasions. The sheriff also explained that the gun had a safety and could not discharge with the safety on. The safety was off during each of his tests. Finally, the sheriff stated that each trigger had approximately a seven-pound trigger pull.
  No suicide notes were found. Mr. Dick had said nothing to his relatives or friends concerning suicide. He left no will.
  At the conclusion of the evidence, respondent unsuccessfully moved for a directed verdict. The court charged the jury that under state law accidental death should be presumed and that respondent had the burden to show by a fair preponderance of the evidence that Dick committed suicide. The jury returned a verdict of $7,500 for petitioner. Respondent’s motions for judgment notwithstanding the verdict and for new trial were denied.
  In this Court and before the Court of Appeals, both parties assumed that the propriety of the District Court’s refusal to grant respondent’s motions was a matter of North Dakota law. Under that law, it is dear that under the circumstances present in this case a presumption arises, which has the weight of affirmative evidence, that death was accidental. Svihovec v. Woodmen Accident Co., 69 N. D. 259, 285 N. W. 447. See Paulsen v. Modern Woodmen of America, 21 N. D. 235, 130 N. W. 231; Clemens v. Royal Neighbors of America, 14 N. D. 116, 103 N. W. 402; Stevens v. Continental Casualty Co., 12 N. D. 463, 97 N. W. 862. Proof of coverage and of-death by gunshot wound shifts the burden to the insurer to establish that the death of the insured was due to his suicide. Svihovec v. Woodmen Accident Co., supra. Under North Dakota law, this presumption does not disappear once the insurer presents any evidence of suicide. Ibid. Rather, the presumed fact (accidental death) continues and a plaintiff is entitled to affirmative instructions to the jury concerning its existence and weight.- This is not to say that under North Dakota law the presumption of acci-. dental death may not be overcome by so much evidence that the insurer is entitled to a directed verdict. For it is clear that where “there is no evidence in the record that can be said to be inconsistent with the conclusion of death by suicide,” or “the facts and circumstances surrounding the death [can] not be reconciled with any reasonable theory of accidental or nonin ten tional injury,” the state court may direct a verdict for the insurer even though the insurer is charged with the burden of proving that death was caused by suicide. These state rules determine when the evidence in a “suicide” case is sufficient to go to a jury. They are not directed at determining when the presumption of accidental death is rebutted, and thus excised from the case, because, as stated above, the presumed fact of accidental death continues throughout the trial and has the weight of affirmative evidence.
  The Court of Appeals, in its opinion, reviewed the evidence in detail and resolved at least one disputed, point in respondent’s favor. It found, as “definitely established by the evidence,” that “neither barrel [of the shotgun] could have been fired unless someone or something either pulled or pushed one of the triggers.” It stated that “[o]ne can believe that even an experienced hunter might accidentally shoot himself once, but the asserted theory that he could accidentally shoot himself first with one barrel and then with the other stretches credulity beyond the breaking point.” And it concluded that the facts and circumstances could not “be reconciled with any reasonable theory of accident, and that, under the evidence, the question whether the death was accidental was not a question of fact for the jury.” Judgment was reversed with directions to dismiss the complaint. 252 F. 2d 43. We granted certiorari, 357 U. S. 925.
  Lurking in this case is the' question whether it is proper tó apply a state or federal test of sufficiency of the evidence to support a jury verdict where federal jurisdiction is'rested on. diversity of citizenship. On this question, the lower courts are not in agreement. Compare Rowe v. Pennsylvania Greyhound Lines, 231 F. 2d 922; Cooper v. Brown, 126 F. 2d 874; Lovas v. General Motors Corp., 212 F. 2d 805, with Davis Frozen Foods v. Norfolk Southern R. Co., 204 F. 2d 839; Reuter v. Eastern Air Lines, 226 F. 2d 443; Diederich v. American News Co., 128 F. 2d 144. And see Morgan, Choice of Law Governing Proof, 58 Harv. L. Rev. 153, 174, and 5 Moore’s Federal Practice (2d ed. 1951) § 38.10. But the question is not properly here for decision because, in the briefs and arguments in this Court, both parties assumed that the North Dakota standard applied. Moreover, although the Court of Appeals appears to have applied., the state standard, that court did not discuss the issue. Under these circumstances, we will not reach out to decide this important question particularly where, in the context of this case, the two standards are substantially the same. A decision 'as to which standard should be applied can well be left to another case where the question is briefed and argued. This case can be decided on the simple issue stated at the outset of the opinion.
  In our view, the Court of Appeals improperly reversed the judgment of the District Court. It committed its basic error in resolving a factual dispute in favor of respondent that the shotgun would not fire unless someone or something pulled the triggers. Petitioner’s. evidence on this score, despite the “tests” performed by the sheriff, could support a jury conclusion that the gun might have fired accidentally from other causes. Once an accidental discharge is possible, a jury could rationally conceive of a number of explanations of accidental death which were consistent with evidence which the .jury might well have believed showed the overwhelming improbability of suicide. The record indisputably shows lack, of motive — in fact there is' affirmative evidence from which the jury could infer that Dick was a most unlikely suicide prospect. He was relatively healthy, financially secure, happily married, well liked, and apparently emotionally stable. He left nothing behind to indicate that he had committed suicide and nothing in his conduct before death indicated an intention to destroy himself. The timing of the death, while in the midst of normal chores and immediately preceding a planned appointment with neighbors, militates against such a conclusion. Dick’s presence in the shed and the accessibility of. the gun are explicable in view of the fact that dogs had previously attacked his sheep and the fact that the door in the shed provided a convenient exit to the adjoining fields. And a jury could well.believe it improbable that a man would not even bother to remove his bulky gloves, of thick jacket, when he intended to commit suicide even though those articles of clothing made it difficult to turn the gun on himself.
  In a case like this one, North Dakota presumes that death was accidental and places on the insurer the burden of proving that death resulted from suicide. Stevens v. Continental Casualty Co., supra; Paulsen v. Modern Woodmen of America, supra. Under the Erie rule; presumptions (and their effects) and burden of proof are “substantive” and hence respondent was required to shoulder the burden during the instant trial. Palmer v. Hoffman, 318 U. S. 109; Cities Service Oil Co. v. Dunlap, 308 U. S. 208. And see Balchunas v. Palmer, 151 F. 2d 842; Sylvania Electric Products v. Barker, 228 F. 2d 842; Matsumoto v. Chicago & N. W. R. Co., 168 F. 2d 496. After all the evidence was’ in, the district judge, who was intimately concerned with the trial and who has a firsthand knowledge of the applicable state principles, believed that the ^case should go to the jury. Under all the circumstances, we believe that he was correct and that reasonable men cCuld conclude that the respondent failed to satisfy 'its burden of showing" that death resulted from suicide.
  Reversed.
  Mb. Justice Harlan took no part in the consideration or decision of this case.
  The gun was a Stevens, 12 gauge, double barreled shotgun with two triggers placed one behind the other. It weighed approximately seven pounds. It had an over-all length of 46 inches and measured 32 inches from muzzle to triggers. '
  The sheriff stated that he did not “pretend to be an expert as far as shotguns are concerned.” His tests consisted of dropping the gun with the muzzle down ten times from a height of ten inches and holding the guij with the butt down, about ten inches from the floor and 'dropping it on a board eight or ten times. He also placed the gun, in a normal shooting position against his shoulder and swung the barrel against an obstacle three or four times.
  This statement of the presumption and its weight accords with the requirements of N. D. Rev. Code, 1943, § 31-1101, which provides:
  “A presumption, unless declared by law to be conclusive, may be. controverted by other direct or indirect evidence but unless so controverted, the jurors are bound to find according to the presumption.”
  Respondent’s argument below that the court should adopt the “modern” rule on the effect of presumptions, see, e..g.,9 Wigmore On. Evidence (3d ed. 1940) § 2491, wp,s rejected. The “modern” rule was applied by this Court in New York Life Ins. Co. v. Gamer, 303 U. S. 161, a decision predating Erie R. Co. v. Tompkins, 304 U. S. 64. For the subsequent history of the Gamer case, see 106 F. 2d 375.
  Svihovec v. Woodmen Accident Co., supra; Clemens v. Royal Neighbors of America, supra.
  The Court of Appeals admitted the improbability of Dick’s being able to pull the triggers with bulky gloves on but believed that this was offset by the probability that he used the screwdriver to push the triggers. This resolution of the facts seems strained indeed. The presence of the screwdriver was accounted for by testimony indicating that, it- was used to open the silage shed door. And the jury could reject as improbable the court’s implicit theory that a man mortally wounded in the chest and bulkily clothed could hold a heavy shotgun at arm’s length and shoot off his head particularly when he was wearing heavy gloves that could only be inserted in the trigger guard with difficulty.
  Respondent argued that the North Dakota rule on presumptions should be abandoned in favor of the “modern” rule, see note 4, supra, but the record does not show that it argued' for the application of the federal standard of sufficiency of the evidence.
  Compare Brady v. Southern R. Co., 320 U. S. 476, 479-480,- and Bailey v. Central Vermont R. Co., 319 U. S. 350, 353, with Svihovec v. Woodmen Accident Co., supra.
  Erie R. Co. v. Tompkins, 304 U. S. 64.