BOWNES, Senior Circuit Judge.

This appeal requires us to decide, for a third time, whether the district court correctly decided this Federal Tort Claims Act ("FTCA") suit in favor of the government. Once again, we are of the opinion that the district court's ruling is not sustainable. We therefore vacate the judgment and remand this matter for further proceedings. We also direct that the proceedings take place before a different district court judge.

I.

On October 10, 1979, while working at the Somersworth Shoe Company plant in Somersworth, New Hampshire, plaintiff-appellant Gail Merchant Irving sustained severe injuries when her hair became entangled in the unguarded rotating shaft of a die-out machine located next to her work station. The accident occurred when plaintiff bent over to pick up a glove she had dropped near the machine.

On October 7, 1981, plaintiff filed suit against the United States under the FTCA. She claimed that inspectors from the Occupational Safety and Health Administration ("OSHA") had twice negligently failed to notice a dangerous condition which was an undisputedly serious violation of OSHA safety standards — i.e., that the rotating shaft on the die-out machine was unguarded. Her theory of liability was that Somersworth would have corrected the dangerous condition prior to her accident had it been given notice of the violation during either of the two inspections. The inspections at issue took place in 1975 and 1978.

From the beginning, the government has argued that the district court lacked subject matter jurisdiction over this case because the actions of the OSHA inspectors were protected by the "discretionary function" exception to the FTCA's waiver of sovereign immunity. See 28 U.S.C. § 2680(a); see also Irving v. United States, 909 F.2d 598, 600 (1st Cir. 1990) (because discretionary function exception effectively reinstates sovereign immunity, cases falling within it are dismissed for lack of subject matter jurisdiction) (" Irving I"). Section 2680(a) exempts from the FTCA's waiver.

Any claim based upon an act or omission of an employee of the Government, exercising due care, in the execution of a statute or regulation, whether or not such statute or regulation be valid, or based upon the exercise or performance or the failure to exercise or perform a discretionary function or duty on the part of a federal agency or an employee of the Government, whether or not the discretion involved be abused.

The government's initial challenge to the district court's subject matter jurisdiction was presented in a motion to dismiss. On February 22, 1982, the court denied the motion. See 532 F. Supp. 840 (D.N.H. 1982). Prior to trial, but after the Supreme Court handed down an opinion elaborating upon the scope of the discretionary function exception, see United States v. Varig Airlines, 467 U.S. 797, 104 S.Ct. 2755, 81 L.Ed.2d 660 (1984), the government renewed its motion to dismiss. On August 8, 1984, the district court denied this second motion.

A bench trial on the merits of plaintiff's claim began on February 11, 1985, and concluded on February 14, 1985. For nearly three years, the district court had the matter under advisement. Finally, on January 27, 1988, the court dismissed the suit without reaching the merits. The court, citing intervening circuit authority, reversed its earlier rulings to the contrary effect and concluded that the discretionary function exception applied to the OSHA inspections.

The court's dismissal order came shortly before the Supreme Court decided Berkovitz v. United States, 486 U.S. 531, 108 S.Ct. 1954, 100 L.Ed.2d 531 (1988). On plaintiff's initial appeal, we vacated the dismissal and remanded the matter for further consideration in light of Berkovitz. Irving v. United States, 867 F.2d 606 (1st Cir. 1988) (unpublished order). We directed:

On remand . . . the district court should first consider whether, viewing the evidence in the light most favorable to the appellant, its decision to dismiss remains correct after Berkovitz. A determination by the district court that its initial decision does not survive Berkovitz does not of course preclude a later finding of immunity based upon the court's factual findings. If the district court ultimately finds that the OSHA employees had discretion in conducting their inspection and that the discretion involved considerations of policy, it should grant the government immunity.

Id., slip op. at 3-4.

The district court did not follow our instructions. It did not discuss whether, in light of Berkovitz, plaintiff's allegations were sufficient to state a claim falling outside the discretionary function exception. Nor did it analyze whether plaintiff's proof was sufficient to sustain her allegations. Instead, the court simply compared the facts here with the facts of a then-recent, post- Berkovitz OSHA case in which the Fifth Circuit had found the discretionary function exception to apply, see Galvin v. OSHA, 860 F.2d 181 (5th Cir. 1988), and ruled that the suit was within the scope of the exception.

Plaintiff again appealed, and again prevailed on appeal. See Irving I, 909 F.2d at 605. We pointed out that, under Berkovitz, the discretionary function exception applies "only if the challenged action 'is a matter of choice for the acting employee' and 'if the action challenged in the case involves the permissible exercise of policy judgment.'" Id. at 601 (quoting Berkovitz, 486 U.S. at 536, 537, 108 S.Ct. at 1958, 1959). Applying this rule, we first found plaintiff's allegation that OSHA policy required the inspectors to notice the violation at issue here adequate to state a claim that the discretionary function exception did not apply. Id. at 601-03 (analyzing pertinent case law). We next assessed the evidence and concluded that it was sufficient for a finding in plaintiff's favor on the discretionary function question. Id. at 603-05. We therefore vacated and remanded for a second time. In so doing, we stated:

[A]n issue of fact lingers in the record: whether OSHA policy left the thoroughness of inspections a matter of choice for its compliance officers. There is some evidence, viewed in the light most favorable to the plaintiff, that the thoroughness of inspections was not left up to the individual compliance officers, and that the compliance officers did not have policy-level discretion to fail to note and tell the employer about the violation which allegedly was the cause of Ms. Irving's injuries. The district court should have made findings resolving this issue, in conformity with the directions of this court on the earlier appeal.

Id. at 605. Our opinion issued on July 25, 1990.

For nearly four years, the district court did not respond to the second remand. Finally, on June 27, 1994, the court issued a memorandum opinion. Once again, the court declined to follow our mandate. Instead, it addressed the merits of plaintiff's claim. After reviewing its trial notes and a partial transcript of the 1985 trial, the court found that, at the time of the 1975 and 1978 OSHA inspections, the die-out machine was "some two feet closer to the wall to its rear" than it was on the day of plaintiff's accident. This finding led the court to conclude that the offending rotating shaft was permissibly "guarded by location" — i.e., that "it was then in such a location that employees working near it would not be exposed to injury" — at the time of the OSHA inspections. As the court explained, "[The machine's] nearness to the wall to its rear would prevent access and probable injury." Accordingly, the court found that no negligent act or omission on the part of any OSHA employee occurred during the 1975 and 1978 inspections. In the court's view, this finding obviated any need to resolve the discretionary function question. Judgment was entered for the government.

II.

On appeal, plaintiff makes two arguments. First, she contends that the district court's guarded-by-location finding is clearly erroneous and/or predicated upon errors of law. Second, she asserts that "the undue delay of nine and one-third years between the bench trial and the final decision on the merits rendered the court's findings of fact unreliable and also violated the plaintiff's right to access to the courts, due process, and fundamental fairness as guaranteed by the United States Constitution." For its part, the government renews its argument that the actions of the OSHA inspectors fell within the FTCA's discretionary function exception.

Because the government's argument puts the district court's subject matter jurisdiction into issue, we begin with the last of the three appellate arguments.

A. The Discretionary Function Exception

It is axiomatic that, "in a multi-panel circuit, newly constituted panels, generally speaking, are bound by prior decisions on point." Metcalf Eddy, Inc. v. Puerto Rico Aqueduct and Sewer Auth., 991 F.2d 935, 939 n. 3 (1st Cir. 1993). This rule does not apply, however, when the decision is subsequently undercut by controlling authority — e.g., a Supreme Court opinion, an en banc opinion of the circuit court, or a statutory overruling. Metcalf Eddy, Inc. v. Puerto Rico Aqueduct and Sewer Auth., 945 F.2d 10, 12 (1st Cir. 1991), rev'd on other grounds, ___ U.S. ___, 113 S.Ct. 684, 121 L.Ed.2d 605 (1993). Nor does it apply in those rare situations "where newly emergent authority, although not directly controlling, nevertheless offers a convincing reason for believing that the earlier panel, in light of the neoteric developments, would change its course." Id.

The government does not dispute that, under ordinary circumstances, we would be precluded from reexamining whether the discretionary function exception applies here. After all, the panel in Irving I gave the question careful and exhaustive consideration, and concluded that it could not be resolved without further fact finding. Irving I, 909 F.2d at 605. Instead, the government argues: (1) that the factual findings made by the district court in the June 27, 1994 memorandum opinion are sufficient to resolve the outstanding factual issues noted in Irving I; and (2) that the Supreme Court's decision in United States v. Gaubert, 499 U.S. 315, 111 S.Ct. 1267, 113 L.Ed.2d 335 (1991), which was handed down after Irving I, offers convincing reasons to believe that the panel in Irving I would have ruled differently had it had the benefit of the Gaubert opinion. We disagree with both contentions.

The Irving I panel ruled that the applicability of the discretionary function exception could not be decided without findings as to whether OSHA policy left the thoroughness of inspections a matter of choice for individual inspectors, and whether the inspectors had policy-level discretion to fail to note and tell the employer about the violation which allegedly caused plaintiff's injuries. 909 F.2d at 605. The government relies on certain "findings" in the district court's June 27, 1994 memorandum opinion. These findings were: that the OSH Act and its implementing regulations do not themselves provide standards to guide inspectors in the exercise of their authority to search; that there is no statute or regulation requiring OSHA to ensure that all machines in every workplace are properly guarded; that the OSHA Field Operations Manual recognizes that inspections may vary considerably in scope and detail, depending upon the circumstances in each case; and that it is a judgment call whether a certain machine is in violation of OSHA standards. We do not think that these findings address the concerns noted in Irving I.

The Irving I panel explicitly acknowledged that if "the statute and the formal regulations [were] the only standards guiding the compliance officer's conduct, the discretionary function exception would apply." Id. at 603. The question in this case, however, revolves around OSHA policy — as opposed to the statute and formal regulations — in 1975 and 1978. Id. The referenced findings in no way speak to OSHA policy during these two years. Similarly, while the OSHA Field Operations Manual notes that inspections may vary considerably in scope and detail, it does not indicate that the individual inspectors were themselves to decide on the scope and detail of each inspection. And the general statement that it is a judgment call whether a certain machine is in violation of OSHA standards is not, when read in context, a finding at all. It is, rather, a reiteration of the testimony of Francis Amirault, who was the Area Director of OSHA at all times relevant to this litigation. The Irving I panel was well aware of this testimony, and did not view it as dispositive. See id. at 604-05. For reasons explained more fully below, we are not free to revisit this conclusion. See Metcalf Eddy, 991 F.2d at 939 n. 3.

As to the assertion regarding Gaubert, we note that the government has not attempted to explain how Gaubert renders Irving I incorrect or obsolete. Ordinarily, this would lead us to conclude that the argument is waived. See United States v. Zannino, 895 F.2d 1, 17 (1st Cir.) ("issues adverted to in a perfunctory manner, unaccompanied by some effort at developed argumentation, are deemed waived"), cert. denied, 494 U.S. 1082, 110 S.Ct. 1814, 108 L.Ed.2d 944 (1990). Because the question implicates the district court's subject matter jurisdiction, however, we have independently analyzed whether Gaubert offers a convincing reason for concluding that the Irving I panel would change its course. See Metcalf Eddy, 945 F.2d at 12. We discern no such reason.

Gaubert was concerned primarily with correcting the lower court's misperception that operational or management decisions cannot be policy decisions protected by the discretionary function exception. See 499 U.S. at 325-26, 111 S.Ct. at 1275. No such misperception is apparent in Irving I. Moreover, Gaubert explicitly reaffirmed the legal basis on which the holding in Irving I was constructed: that "the requirement of judgment or choice is not satisfied if a 'federal statute, regulation, or policy specifically prescribes a course of action for an employee to follow,' because 'the employee has no rightful option but to adhere to the directive.'" Gaubert, 499 U.S. at 322, 111 S.Ct. at 1273 (emphasis supplied) (quoting Berkovitz, 486 U.S. at 536, 108 S.Ct. at 1958-59). Applying this rule, the panel in Irving I first noted plaintiff's allegation that OSHA had a policy requiring its inspectors to notice safety violations within the four walls of the inspected plant. 909 F.2d at 603. The panel then found that there was sufficient evidence in the record for a rational fact finder to credit this allegation, and held that the discretionary function question could not be answered until the trial court decided whether or not to credit the allegation. Id. at 603-05. There is nothing new in Gaubert that calls this analysis into question. We therefore see no reason to conclude that the panel would have decided Irving I any differently had Gaubert been previously issued.

The discretionary function doctrine is fraught with difficulty, and the Supreme Court or Congress may some day decide that the analysis in Irving I is incorrect. Unless and until that day arrives, however, or unless and until we revisit the question as an en banc court, Irving I remains binding on all newly constituted panels in this Circuit. Accordingly, we reject the government's argument that the discretionary function question can be decided in its favor without further fact finding.

B. The Guarded-by-Location Finding

In reviewing a factual finding made by a district judge in connection with a bench trial, we almost always apply the clear-error standard of review. See Fed.R.Civ.P. 52(a). Under this standard, we give the finding effect unless we are "'left with the definite and firm conviction that a mistake has been committed.'" Anderson v. City of Bessemer City, 470 U.S. 564, 573, 105 S.Ct. 1504, 1511, 84 L.Ed.2d 518 (1985) (quoting United States v. United States Gypsum Co., 333 U.S. 364, 395, 68 S.Ct. 525, 542, 92 L.Ed. 746 (1948)). Thus, "[w]here there are two permissible views of the evidence, the factfinder's choice between them cannot be clearly erroneous." Id.

Of course, the deference mandated by Rule 52(a) has its limits. For example, the Rule clearly presumes that a sustainable finding will be based upon properly admitted evidence. And the Supreme Court has indicated that if a reviewing court is firmly convinced that a finding is mistaken, it should reverse the finding even where there is evidence to support it. See Anderson, 470 U.S. at 573, 105 S.Ct. at 1511; United States Gypsum, 333 U.S. at 395, 68 S.Ct. at 542.

Here, the court reached its conclusion that the rotating shaft of the die-out machine was guarded by location at the time of the 1975 and 1978 OSHA inspections by analyzing the inspections separately. With regard to the 1975 inspection, the court's finding was premised on a subsidiary finding that "[p]rior to the spring of 1977, the offending machine had been positioned some two feet closer to the wall to its rear. Between that date and the spring of 1979, it had been moved forward to the position it occupied at the time of plaintiff's accident." As the basis for so finding, the court stated: "The evidence as to the prior location of the 'die-out' machine came from the testimony of Robert [sic] Couture." In rejecting plaintiff's request that it reconsider the finding, the court elaborated:

Although [Couture's] testimony was not transcribed, the court, as is its custom, took contemporaneous trial notes of the testimony of each witness. Mr. Couture's testimony was therein recorded. In light of such testimony, the court credited that testimony over the testimony of Igor Paul that Mr. Paul was of the opinion that the machine had not been moved.

The transcript of Couture's actual testimony, which has been provided to this court on appeal, reveals serious errors in the district court's trial notes.

First, Couture did not testify that the dieout machine had been moved; he testified that "it might have been moved." Second, Couture did not testify that the machine had been moved two feet; he testified that it might have been moved "one or two feet." And third, Couture did not testify that the machine had been moved between the spring of 1977 and the spring of 1979; he testified that he "really [did not] remember" when any movement might have taken place.

To be sure, there was evidence in the record tending to support the district court's finding. This "evidence," however, was hearsay testimony of OSHA compliance officer O'Connell regarding statements Couture allegedly made a few days prior to trial. On redirect examination by plaintiff's counsel, O'Connell testified that, just before trial, Couture told him that the machine had been moved two feet at some point in the two years preceding the spring of 1979. In light of Couture's testimony at trial (which was inconsistent with O'Connell's), the probative value of O'Connell's testimony is open to serious question. And much more importantly, the district court does not appear to have relied upon O'Connell's testimony in finding that the rotating shaft was guarded by location at the time of the 1975 inspection.

In the end, we have little confidence in the trial court's finding regarding the 1975 inspection. The court fundamentally misconstrued the testimony upon which it explicitly and exclusively relied in making the finding. Moreover, the nine and one-third-year delay between trial and the finding significantly undercuts the reason for presuming that the trial court was in a superior position to judge the demeanor and credibility of the relevant witnesses. Cf. Williams v. Poulos, 11 F.3d 271, 278 (1st Cir. 1993). Thus, even though the record evidence is inconclusive as to location, we set aside the finding that the die-out machine's rotating shaft was guarded by location at the time of the 1975 inspection.

Having made this determination, we do not need to decide any of the other issues in this case. This means that we need not determine whether: (1) the district court's patently erroneous reliance upon deposition testimony which had not been read into the record at trial, see Secretary of Labor v. DeSisto, 929 F.2d 789, 796-97 (1st Cir. 1991) (documents attached to summary judgment motions are not evidence unless admitted at trial), requires reversal of the finding that the rotating shaft was guarded by location in 1978; (2) the court erroneously failed to give plaintiff the benefit of a favorable state law principle — i.e., that a prior or subsequent location "is evidential of a later or earlier one," see Dube v. Bickford, 92 N.H. 362, 31 A.2d 64, 66 (1943); or (3) the delay in deciding this case was so substantial that it deprived plaintiff of her constitutional rights.

Plaintiff's theory of liability was that Somersworth would have guarded the rotating shaft had it been informed of the dangerous condition in 1975 or 1978. The court rejected this claim on the basis of its findings that the rotating shaft was, in fact, guarded by location in 1975 and 1978. The defective finding that the shaft was guarded by location in 1975 was therefore necessary to the court's entry of judgment in favor of the government. For this reason alone, the judgment cannot stand.

III.

There still remains the question of relief. If this were an ordinary case, we would remand the matter to the trial court for further proceedings consistent with our opinion. Obviously, this has not been an ordinary case for quite some time. Thus, despite the difficulties inherent in retrying a case which was tried over ten years ago, and which arises out of injuries suffered more than fourteen years ago, we think fundamental fairness dictates that plaintiff be granted her request for a trial de novo before a different district court judge. No finding from the previous trial should be given preclusive effect in the new trial, and the government is free to renew its argument that the inspectors' actions fell within the discretionary function exception, as well as its argument that the machine was guarded by location during the period when the OSHA inspections occurred. We commit to the new judge's discretion the question whether to proceed solely on the current record.

For the reasons stated above, the judgment of the district court is vacated. This matter is remanded to a different district court judge for further proceedings consistent with this opinion. Plaintiff is entitled to her costs.