This suit tо cancel mineral leases and to obtain damages incurred as a result of their alleged breach was commenced in Louisiana state court, and removed by the defendant, Superior Oil Company, 1 to federal court on the basis of diversity of citizenship. After a careful consideration of Louisiana law, the experienced trial judge rendered a summary judgment for the defendant. While we conclude that the trial court was correct in its analysis of Louisiana law, we reverse the summary judgment and remand because the plaintiff is entitled to a jury trial of a controlling issue. 2
I.
The objective facts are not in dispute. 3 Adam Nunez and his son, Adam G. Nunez, each owned an undivided one-fourth interest in a piece of property leased to Superior for mineral development. On May 2, 1971, the father died and the son began endorsing his father’s royalty checks, with the added notation “by Adam G. Nunez, Administrator, for deposit only to the Estate of Adam Nunez.” Over six months later, on October 21, 1971, K. R. Richardson, a senior clerk at Superior, discovered that the endorsement was executed in a representative capacity, and ordered royalty payments to the father stopped. He wrote the son, who is a lawyer, and asked for various documents relating to the father’s succession. These documents were supplied, and the company’s attorney approved further payments to the administrator of the succession.
Whenever there is any change in the division of the royalty from a lease, it is Superi- or’s policy, in accordance with industry custom, to send an agreement to the royalty owners stating how the royalty is to be divided, and to ask them to sign it. The company recognizes that it is nоt necessary in many cases that a division order be exe *1122 cuted; it was not considered necessary in this case, but it nonetheless follows the practice of mailing a division order in the hope that the lessees will sign it and thus ratify the proposed new apportionment of royalty. Adam G. Nunez stated at oral argument that he never signs division orders; he sees no advantage to him, as a lessor, in doing so and the company has no right to require it. Accordingly, Superior followed its procedure and sent a royalty division order to Adam G. Nunez, as administrator of his father’s succession, but he neither signed it nor returned it to the company.
On April 6, 1972, Adam G. Nunez sent Superior a copy of a judgment of possession recognizing him as the sole heir of all his father’s property, including the royalty interest, and a letter requesting that payments of his father’s intеrest be made to him. On June 15, 1972, the company sent him a second royalty division order; this too was neither signed nor returned.
When the company mails a division order, it usually places a copy in its tickler system to remind its employees to check within 30 to 60 days to ensure that royalty payments are resumed even if the division order has not been returned. On this occasion, through oversight, the copy was not placed in the reminder system. Because of this failure, none of the company’s employees became conscious of the fact that the division order had not been returned and that payments had not been resumed. The error was discovered during an internal audit on February 20,1974; as a result, the company sent Nunez the unpaid royalties with interest computed at the rate of seven percent per annum. On March 14,1974, he sеnt the company a letter demanding acknowledgement of cancellation of the lease. Following the company’s refusal to oblige, this suit was filed. After the case was removed to federal court, the plaintiff demanded a jury trial.
II.
Under Louisiana law, the lessee’s failure to pay production royalties for an
appreciable length of time without justification
amounts to an active breach which terminates the lease.
Wilson v. Sun Oil Co.,
La.1974,
The principle just stated includes two general terms that require further amplification: what length of time is appreciable, and, under what circumstances is a breach justifiable. The Louisiana cases indicated that each issue must be considered in the context of the unique facts and circumstances of the case in which it arises.
Faw-vor, supra.
Because Superior concedes that its delay was appreciable, we focus on justifiability. Delay has been considered “justifiable” when the lessor shows that it is due to “adequate reason,”
Fontenot v. Sunray Mid-Continent Oil Co.,
La.App.1967,
The trial court granted summary judgment on the basis that the delay was attributable to, and “justified” by, the administrative procedures designed to reflect the change in ownership and the subsequent inadvertent error in filing; hence, the delay constituted only a passive breach. The court also concluded that the letter of April 6,1972 did not constitute a demand or “putting in default” because it did not put the defendant on notice that the plaintiff considered the lease terminated. Because Superior had not been put in default for the passive breach, the plaintiff was not entitled to cancellation.
There can be little doubt that the trial court’s factual conclusions were not clearly erroneous; the question is whether the court was correct in rendering summary judgment determining that Superior’s delay was justifiable, or whether that issue required resolution by a jury.
III.
Our appraisal must follow the commandment that summary judgment is appropriate only when no material issues of
fact
are in dispute.
A. M. R. Enterprises, Inc. v. United Postal Savings Assoc.,
5 Cir. 1978,
There is no litmus that infallibly distinguishes those issues that are “factual” from those that are “legal” or “mixed.” When all those material facts susceptible of objective determination are known, there may be inferences or conclusions to be drawn from them. Many observations that may appear superficially to be factual are the result of inference, viewpoint, and judgment. At ends of the spectrum, it may be relatively easy to separate fact and law, but, as we approach the point where facts and the application of legal rule to them blend, appraising evidentiary facts in terms of their legal consequences and “applying” law to fact become inseparable processes. In some instances where facts may assume infinite variety, legal rules are deliberately stated in a fashion calling for the application of judgment. Thus, in a suit for personal injury from an automobile accident, it might be ascertained, or even stipulated, that the defendant was driving at 50 miles per hour on a certain road at 6:00 p. m. on a rainy January day. The trier of fact must still decide whether this is “negligence.” Therefore, the availability of summary judgment depends upon more thаn an abstract denomination of disputed material issues as “factual” or “legal” or “mixed;” it may turn on whether the application of legal criteria necessarily require judgmental evaluation by the trier of fact, or, to put it another way, whether the trial will require a judge/jury separation of issues.
If decision is to be reached by the court, and there are no issues of witness credibility, the court may concludе on the basis of the affidavits, depositions, and stipulations before it, that there are no genuine
*1124
issues of material fact, even though decision may depend on inferences to be drawn from what has been incontrovertibly proved. Under those circumstances, which may be rare, the judge who is also the trier of fact may be warranted in concluding that there was or was not negligence, or that someone acted reasonably or unreasonably, or, as is the case here, that delay under the circumstances proved is justified or unjustified, even if that conclusion is deemed “factual” or involves a “mixed question of fact and law.” A trial on the merits would reveal no additional data. Hearing and viewing the witnesses subject to cross-examination would not aid the determination if there are neither issues of credibility nor сontroversies with respect to the substance of the proposed testimony. The judge, as trier of fact, is in a position to and ought to draw his inferences without resort to the expense of trial.
Compare Avondale Shipyards, Inc. v. Vessel Thomas E. Cuffe,
E.D.La., 1977,
But, where a jury is called for, the litigants are entitled to have the jury draw those inferences or conclusions that are appropriate grist for juries. Summary judgment “was not intended to . deprive a litigant of, or at all еncroach upon, his right to a jury trial. Judges in giving its flexible provisions effect must do so with this essential limitation constantly in mind.”
Whitaker v. Coleman,
5 Cir. 1940,
Juries must consider not only “questions of fact in dispute, [but] questions of conflicting inferences from undisputed facts.”
Buffalo Insurance Co.
v.
Spach,
5 Cir. 1960,
Thus, where, as here, the evidentiary facts are not disputed, a court in a non-jury case may grant summary judgment if trial would not enhance its ability to draw inferences and conclusions. But summary judgment is not appropriate if the same case is to be tried to a jury, and the inferences and conclusions to be drawn are genuinely disputed. To put it in another fashion, whether disputed issues are issues of “fact” for purposes of Rule 56 depends not only on the state of the evidence and the nature of the issue but hinges also on whether the litigants have a right to a jury determination. Whether summary judgment was appropriate here depends, therefore, upon whether the plaintiff was entitled to a jury trial, and, also, whether the determination with respect to justification for the delay in paying royalties is a decision that must be made by the jury rather than the court. 6 These questions are in *1125 terrelated, and it is helpful to discuss the second one first.
IV.
Louisiana courts have considered the justifiability of a delay in royalty payments to be an issue of fact.
See, e. g., Mecom v. Mobil Oil Corp.,
La.App.1974,
However, although the substantive issues are governed by state law pursuant to Erie,
8
federal law governs the allocation of issues raised between judge and jury. “It cannot be gainsaid that there is a strong federal policy against allowing state rules to disrupt the judge-jury relationship in the federal courts.”
Byrd v. Blue Ridge Rural Electric Cooperative,
1958,
The categories of “questions of law” and “questions of fact” have been the traditional tоuchstones by which federal courts have purported to allocate decision-making between judge and jury.
12
Dimick v. Schiedt,
*1126
1935,
Whether the inference is one for the court or one for the jury depends ultimately upon which decision-maker can best resolve the issue.
See United States v. J. B. Williams Co., Inc., supra,
If the inference to be drawn requires “experience with the mainsprings of human conduct” and reference to “the data of practiсal human experience,”
13
Commissioner of Internal Revenue v. Duberstein,
1960,
Apart from nature of the issue, the courts have suggested that, if reasonable persons can draw conflicting inferences from otherwise undisputed facts, the collective wisdom of the jury ought be relied upon.
14
“Where uncertainty arises either from a conflict of testimony or because the facts being undisputed, fair-minded men may honestly draw different conclusiоns from them, the question is not one of law, but of fact to be
*1127
settled by the jury.”
Best v. District of Columbia,
1934,
Whether the delay in payments was “justified” by the clerical error depends in large measure upon whether Superior acted reasonably under the circumstances. See Alvord v. Sun Oil Co., supra; Hebert v. Sun Oil Co., supra. It requires the determination of whether a particular standard defined by the Louisiana jurisprudence and differing perhaps only in degree from such other general standards as negligenсe, foreseeability, reasonableness or just cause, was violated or maintained. Hence, it involves a determination that either party would be entitled to have submitted to a jury, 15 if he is otherwise entitled to a jury trial.
V.
An action to cancel a mineral lease is equitable in nature.
Kerr-McGee Corp. v. Bokum Corp.,
10 Cir. 1972,
However, in addition to cancellation of the lease, plaintiff seeks damages sustained as a résult of the alleged breach. These include the value of the entire production attributable to the Nunez interest from the date of breach, estimated at $103,-712.28, interest on that sum, and, presumably in the alternative, alleged losses suffered due to the increased income tax liability resulting from receipt of the royalties in a lump sum.
Where “equitable and legal claims are joined in the same action, there is a right to jury trial on the legal claims which must not be infringed either by trying the legal issues as incidental to the equitable ones or by a court triаl of a common issue existing between the claims.”
Ross v. Bernard,
1970,
The justification for the failure to pаy royalties must be determined with respect to both the legal and equitable claims. Although the claim for damages cannot succeed unless the lease is cancelled, extenuation is an issue common to both. We do not find “imperative circumstances” that would justify the court in deciding the common issue with respect to the equitable aspect of the case, thus denying a jury trial of that issue.
Dairy Queen, supra,
Accordingly, the order of the trial court granting summary judgment is REVERSED, and this case is REMANDED for further proceedings consistent with this opinion.
Notes
. The occasional reference to “Sun Oil” in the opinion below,
. The plaintiffs appeal raised the issue of whether the court properly applied Louisiana jurisprudence in concluding that Superior was entitled to summary judgment. While enough was said аbout the decisive issue to prevent its preclusion as a matter not properly raised,
see Martinez v. Mathews,
5 Cir. 1976,
We note, too, that the trial judge did what a Louisiana trial judge likely would have done: decide the cаse. The plaintiffs demand for jury trial, however, barred the usual course.
. The plaintiff calls attention to certain disputes about facts but none of these appears at this stage to be genuinely material to decision of the issue presented.
. This is called “putting in default.” LSA-C.C. art. 1911. Savoy v.
Tidewater Oil Co.,
W.D.La. 1963,
. The standard to be applied is, of course, a federal one.
Hanna v. Plumer,
1965,
. Whether the issue is to be decided by a jury or by the court will also affect the standards governing appellate review. Where a jury has tried an issue upon correct instructions, the only inquiry is whether there was sufficient evidence to sustain the findings.
See Security Mut. Cas. Co. v. Affiliated FM Ins. Co.,
8 Cir. 1972,
. The issue of whether violation of an implied obligation to protect from drainage is an active or passive breach is for the court rather than the jury.
Williams v. Humble Oil & Refining Co.,
5 Cir. 1970,
.
Erie R. Co. v. Tompkins,
1938,
.
Simler
v.
Conner,
1963,
.
Herron v. Southern Pac. Co.,
1931,
.
Midland Ins. Co. v. Market Service, Inc.,
5 Cir. 1977,
. The distinction has been traced to the middle of the sixteenth century. Farley, Instructions to Juries — Their Role in the Judicial Process, 42 Yale L.J. 194, 198-199 (1932), referring to Townsend's Case, 1 Plowden 111, 114, 75 Eng.Rep. 173, 178-179 (K.B. 1554). However, the dichotomy has never been a constant one. *1126 See Note, The Changing Role of the Jury in the Nineteenth Century, 74 Yale L.J. 170 (1964).
. Although the court in
Duberstein
was concerned with the appropriate standard for appellate review, rather than with the allocation of decision-making between judge and jury, its analysis is equally applicable to both questions.
See also Bogardus v. Commissioner of Internal Revenue,
1937,
. As Justice Holmes eloquently stated,
When a case arises in which the standard of conduct, pure and simple, is submitted to the jury, the explanation is plain. It is that the court, not entertaining any clear views of public policy applicable to the matter, derives the rule to be applied from daily experience, as it has been agreed that the great body of the law of tort has been derived. But the court further feels that it is not itself possessed of sufficient practical experience to lay dоwn the rule intelligently. It conceives that twelve men taken from the practical part of the community can aid its judgment. Therefore it aids its conscience by taking the opinion of the jury.
Holmes, The Common Law, 123-124 (1881) (footnote omitted).
. The issue of whether the April 1972 letter constituted a “putting in default” or demand under Louisiana law was properly determined by the court, for it not only involves construction of a clear and unambiguous written statement;
compare Pletz v. Christian Herald Ass'n, Inc.,
5 Cir. 1973,
. Where federal law accords the right to jury trial in a diversity case, that right will be respected notwithstanding contrary state law.
Byrd v. Blue Ridge Rural Electric Cooperative,
1958,
