Plaintiff, Charles A. Murray, appeals the United States Magistrate’s1 order granting St. Louis policeman Gerald Leyshock’s motion for judgment notwithstanding the jury verdict (JNOV) on Murray’s state law negligence claim.2 The magistrate concluded that because Leyshock was involved in discretionary conduct at the time of Murray’s injury, Missouri’s official immunity doctrine barred Murray’s recovery as a matter of law.3 We affirm.
*1198I.
On October 15, 1985,4 several police officers executed a search warrant for drug activity at a house in St. Louis. Although they saw a man at a window in the house, there was no response when they knocked. The officers then broke down the door. Detective Leyshock entered first with drawn pistol. Several other police officers followed. Upon seeing Murray in a front room, Detective Leyshock ordered him to place his hands against a refrigerator and “assume the position,” with his feet spread behind him. Leyshock, while standing directly behind Murray, placed his left hand on Murray’s shoulder while holding the gun in his right, and instructed Murray not to move. Then he began to search Murray’s person.
According to Murray, within seconds a large, extremely dangerous, half-wolf, half-Belgian shepherd dog charged out of a dark hallway into the room and attacked Detective Leyshock. The guard dog rushed at Leyshock from between the spread-eagled legs of Murray, and bit Leyshock on the inner thigh. From a twelve-inch distance and with no opportunity to evade, Leyshock fired his gun once at the attacking dog’s head and shoulders. The dog retreated from between Murray’s legs in response. The guard dog then attempted to lunge at Leyshock a second time after the bite. Leyshock fired again at the animal. One of these shots grazed the dog’s muzzle and struck Murray in the calf of the left leg. Leyshock shot a third time at the attack dog as it retreated down the hallway.
Murray brought suit against Detective Leyshock, alleging excessive use of force in violation of 42 U.S.C. § 1983 (1982) and negligence in violation of Missouri law. At trial, Murray introduced evidence of the St. Louis Police Department’s official policy concerning the discharge of firearms.5 A representative of the police department also testified, on Murray’s behalf, that while at the Police Academy, cadets are taught to sight a weapon on the target before firing. The representative further testified that cadets are taught not to shoot negligently, and that shooting negligently violated police procedure. No specific procedure was introduced into evidence on this point. Detective Leyshock admitted at trial that although he had aimed his weapon at the attack dog’s head, he did not sight the weapon before firing.
The jury found against Murray on the § 1983 claim, but ruled in his favor on the state law negligence claim. Leyshock then moved for a judgment notwithstanding the verdict on the state law claim, arguing that the magistrate erred in refusing to grant his motion for a directed verdict on the ground that Leyshock was protected by official immunity.6 The magistrate agreed and granted the JNOV, holding that under Missouri law Leyshock had official immunity because he was engaged in discretionary conduct when he shot at the guard dog. The magistrate then entered judgment nunc pro tunc in favor of Leyshock on both the § 1983 and the state law negligence claims.
II.
In reviewing the magistrate’s grant of JNOV on the facts, we apply the same standard as the magistrate would have applied in the first instance. Morgan v. Arkansas Gazette, 897 F.2d 945, 948 (8th Cir.1990) (citing Cleverly v. Western Elec. Co., 594 F.2d 638, 641 (8th Cir.1979) (per curiam)). In this case, based on the facts found and inferences therefrom in Mur*1199ray’s favor,7 the magistrate ruled as a matter of law that Missouri law supported Leyshock’s claim of official immunity. While we adopt Murray’s version of the facts, our standard of review on the Missouri immunity issue is de novo. Sanders v. Woodruff, 908 F.2d 310, 313 (8th Cir.1990); see also O’Donnell v. Yanchulis, 875 F.2d 1059, 1063-64 (3d Cir.1989) (reviewing de novo district court’s determination of state official immunity as a matter of law).
Where state immunity law is at issue, “it is our practice to defer to the state law ruling of a federal district court sitting in the state whose law is controlling.” Economy Fire & Casualty Co. v. Tri-State Ins. Co., 827 F.2d 373, 375 (8th Cir.1987); accord Pony Express Cab & Bus, Inc. v. Ward, 841 F.2d 207, 209 (8th Cir.1988). Furthermore, in such instances “it is the duty of the federal court to examine the state law and apply it as it anticipates the highest court of the state would.” Economy Fire & Casualty Co., 827 F.2d at 375. We will depart from the lower court’s state law interpretation only if it is “fundamentally deficient in analysis, without a reasonable basis, or contrary to reported state court opinion.” Id.
Murray contends on appeal that the magistrate erred in granting Leyshock’s JNOV motion on the basis of official immunity, because the police officer’s actions were ministerial rather than discretionary, and thus not within the scope of the official immunity doctrine. We review this claim de novo and disagree. We hold that under Missouri law, Detective Leyshock was engaged in discretionary conduct when he discharged his weapon, and therefore official immunity protects him from civil liability for any negligent acts.
Under Missouri law, the official immunity doctrine holds that “a public official is not civilly liable to members of the public for negligence strictly related to the performance of discretionary duties.” Green v. Denison, 738 S.W.2d 861, 865 (Mo.1987). An issue that often arises in official immunity cases is whether the public official was engaged in discretionary or ministerial conduct when the alleged negligence occurred. Discretionary conduct involves “the exercise of reason in the adaptation of means to an end and discretion in determining how or whether an act should be done or course pursued,” whereas ministerial conduct involves an act “of a clerical nature which a public officer is required to perform upon a given state of facts, in a prescribed manner, in obedience to the mandate of legal authority, without regard to his own judgment or opinion concerning the propriety of the act to be performed.” Rustici v. Weidemeyer, 673 S.W.2d 762, 769 (Mo.1984); see also State ex rel. Barthelette v. Sanders, 756 S.W.2d 536, 537 (Mo.1988) (quoting Rustid). In Kanagawa v. State ex rel. Freeman, 685 S.W.2d 831 (Mo.1985), after characterizing the above definitions as “useful guidelines,” the Missouri Supreme Court concluded that
in the final analysis the decision as to whether a public official’s acts are discretionary or ministerial must be determined by the facts of each particular case after weighing such factors as the nature of the official’s duties, the extent to which the acts involve policymaking or the exercise of professional expertise and judgment, and the likely consequences of withholding immunity.
Id. at 836.
Under the well-established Missouri official immunity doctrine, it is highly improbable that the Missouri Supreme Court would have allowed Murray’s state law negligence claim to go to a jury as a matter of law. See Barthelette, 756 S.W.2d at 539 *1200(approving dismissal for failure to state a cause of action where official immunity existed as a matter of law); Green, 738 S.W.2d at 866 (concluding that police officers in shootout had official immunity and sustaining the trial court’s granting of a JNOV); State ex rel. Twiehaus v. Adolf, 706 S.W.2d 443, 449 (Mo.1986) (holding that official immunity existed as a matter of law on the facts presented and granting dismissal).
Murray argues that although Detective Leyshock’s decision to discharge his weapon may be discretionary, the aiming of a weapon is ministerial conduct not protected by official immunity. Applying the definition quoted above, sighting a weapon on a target is not ministerial conduct. It certainly is not an act of a “clerical nature,” nor is it one of the few non-clerical ministerial acts. See Johnson v. Carthell, 631 S.W.2d 923, 927-28 (Mo.Ct.App.1982) (concluding that bus drivers perform a ministerial function). Murray’s major contention is that sighting a weapon is prescribed conduct, performed in obedience to a legal mandate. In support of his argument, Murray cites the rules, policies, and procedures of the St. Louis Police Department and the St. Louis Police Academy. The only formal rule on record is Rule 9.400, which governs when police officers may discharge their weapons.8 Detective Leyshock clearly complied with this rule— he fired his weapon to destroy an animal which Murray admitted was “extremely dangerous.”
The policies and procedures on which Murray so heavily relies are merely instructional techniques from the police academy and other informal practices. Murray argues that the police representative’s testimony that an officer could be reprimanded for firing negligently means a legal mandate exists that requires police officers to sight a target in all instances before firing. One problem with this argument is that the police representative’s and Murray’s use of the phrase “shooting negligently,” and its variants, is not the same as failure to sight the weapon. A second problem with these academy training techniques is that they do not appear to be “designed to apply to a stressful situation, in which immediate action might be necessary to protect lives.” Green, 738 S.W.2d at 867 (footnote omitted). A third problem is that the instructional techniques and informal practices, under Missouri law, would be considered directory rather than mandatory because they merely describe how a firearm should be discharged without prescribing the consequences for failure to use the correct technique. See Norton v. Smith, 782 S.W.2d 775, 778 (Mo.Ct.App.1989). By attempting to bootstrap training practices into prescribed, official procedures, Murray admits one major weakness in his case, namely the lack of a legal mandate that would make sighting a weapon ministerial conduct. By his appeal, Murray is asking this court to create that legal mandate for him. This we will not do because we believe the magistrate properly determined that Detective Leyshock enjoyed official immunity as a matter of law.
Applying the relevant definitions, sighting a weapon on the target is discretionary conduct. Under Green, official immunity exists because sighting the weapon is clearly “strictly related” to what Murray admitted was the discretionary function of discharging a weapon. Green, 738 S.W.2d at 865. Detective Leyshock, when faced with the attack of a dangerous guard dog, had to use his discretion in deciding whether to fire at the dog and how to fire. Detective Leyshock’s judgment informed him there was not enough time to sight his weapon at the guard dog, but he was able to aim at the dog, which was directly in front of him only a foot away. As in the Green case, here Murray is asking the court “to second-guess the officerf] based on [a] post-mor-tem analysis of good police practice.” Id. at 866. The Missouri Supreme Court responded to this by stating: “The doctrine of official immunity was established to protect public officials from just this kind of second-guessing. This is so even though hindsight may demonstrate errors in judg*1201ment which might be branded as negligent by qualified evaluators.” Id.
The “final analysis” the Kanagawa court promulgated also supports the magistrate’s determination that Detective Leysh-oek possessed official immunity. The nature of police work is well-known. By participating in a drug raid, Detective Leysh-oek entered into a situation of great tension. See Green, 738 S.W.2d at 865. If Leyshock had waited long enough to sight his weapon, the attack dog might had disabled him, endangering Leyshock and the other officers present. As the Missouri Supreme Court observed in Green: “[T]here might be danger in delay,.... ” Id. at 865. The next Kanagawa consideration, whether the act involves professional expertise and judgment, is satisfied. Sighting a gun on a target involves instruction and practice, and the shooter’s judgment is required to determine when target acquisition is sufficient for shooting. In this case, Leyshock’s aiming without sighting was sufficient for him to decide to shoot. Finally, the likely consequences of withholding immunity in this situation are calamitous. The Missouri Supreme Court has made explicit the central policy underlying the official immunity doctrine: “[Sjociety’s compelling interest in vigorous and effective administration requires that the law protect those individuals who, in the face of imperfect information and limited resources, must daily exercise their best judgment in conducting the public’s business.” Barthelette, 756 S.W.2d at 538 (citing Kanagawa, 685 S.W.2d at 836). If immunity were withheld from Detective Leyshock, the effect would be to lessen the effectiveness of law enforcement and unreasonably endanger individuals in situations that are already dangerous enough. If forced to ensure complete target acquisition in every possible situation, police officers might be less willing to raid crack houses or challenge armed criminals because of the extra moment it would require to ensure “proper target acquisition.” Again, to paraphrase the Missouri Supreme Court, where there is delay, there is danger. This is not to say that officers should not sight their weapons when possible. But it will not be possible every time, and in those situations when it is not possible, such as this one, we must rely on the officers’ use of their best judgment. It is precisely this judgment the official immunity doctrine is designed to protect.
We find that the magistrate’s interpretation of the Missouri official immunity doctrine is not fundamentally deficient in analysis, was not without a reasonable basis, and was not contrary to reported state court opinion. Accordingly, we affirm.
III.
As a matter of law, the doctrine of official immunity barred any recovery against Detective Leyshock because he was involved in discretionary conduct when he injured Murray. Therefore, the magistrate properly granted Leyshock’s motion for a JNOV on the state law negligence claim. We affirm the entry of judgment.
. The Honorable William S. Bahn, United States Magistrate for the Eastern District of Missouri. Pursuant to 28 U.S.C. § 636(c)(1) (1988), the parties consented to the entry of judgment by a magistrate.
. The jury found in favor of Leyshock on Murray's claim under 42 U.S.C. § 1983 (1982). Leyshock had removed this case from state court based on this claim. Murray abandoned a punitive damages claim before jury submission.
. Leyshock also argued to the magistrate in his motion for a directed verdict and subsequent motion for judgment notwithstanding the ver-diet that he owed no particularized duty to Murray as a bystander and therefore Missouri’s public duty doctrine was applicable. Murray argued that a special relationship (i.e., custody) existed, giving rise to a particularized duty. Although the magistrate discussed, and both parties briefed on appeal the public duty doctrine, in granting Leyshock’s motion for judgment notwithstanding the verdict, the magistrate found only that Leyshock had official immunity. We thus need not reach the public duty issue, but only the state immunity issue.
. Because we must consider the evidence in the light most favorable to the party prevailing on the jury verdict, we adopt Murray’s version of the facts. See infra pp. 1198-99.
. The pertinent portion of the police manual, Rule 9.400, states: "Firearms are to be discharged in the proper performance of police duty only under the following circumstances:
... (b) to destroy seriously injured or dangerous animals when no other method is practical;_” This is the only formal police department policy governing the discharge of firearms. Tr. at 2:4-5.
.Leyshock’s other arguments are not relevant to this appeal.
. With respect to the underlying facts, this standard requires a reviewing court to: (1) consider the evidence in the light most favorable to Murray, who prevailed with the jury; (2) assume the jury resolved all evidentiary conflicts in Murray’s favor; (3) assume as proved all facts which Murray’s evidence tends to prove; (4) give Murray the benefit of all favorable inferences which may reasonably be drawn from the facts proved; and (5) affirm the granting of the JNOV if reasonable persons could not differ as to the conclusions to be drawn from the evidence. Arkansas Gazette, 897 F.2d at 948 (citing Gilkerson v. Toastmaster, 770 F.2d 133, 136 (8th Cir.1985)).
. See supra note 5.