Fоllowing a jury trial of their personal injury claims brought in this Texas diversity suit, plaintiffs-appellants, injured employees of Crown Central Petroleum Company (“Crown Central”), and intervenor-ap-pellant, United States Fidelity & Guaranty Company, appeal a jury verdict for defendant-appellee Phillips Petroleum Company (“Phillips”), claiming errors in the district court’s instructions to the jury. We affirm.
Facts and Proceedings Below
During the 1930’s, Phillips developed a chemical process to produce “alkylates,” the end result of a chemical process whereby hydrofluoric acid acts as a catalyst on certain hydrocarbons. A type of these alk-ylates was subsequently used as aviation fuel during World War II. These alkylates are currently used as octane enhancers for gasoline, recreational fuels (such as charcoal lighter fluids), and solvents.
Following World War II, Phillips licensed its process to other refiners for use in hydrofluoric plants, and seventy-two such agreements were concluded. In 1964, Phillips reached an agreement with Crown Central. Crown Central then used the information obtained from Phillips to build an alkylation unit, and it hired Foster-Wheeler, an outside firm, to draw up mechanical designs for the unit and later to construct it. Under the contract between Phillips and Crown Central, Phillips gave Crown Central both the technical information needed to run the unit and the nonexclusive use of its patents on the alkylation process. Phillips also gave Crown Central technical advice, a process “flow sheet,” material specifications and recommendations, and an operating and safety manual for the unit. Additionally, Phillips trained the first Crown Central operators of the unit.
Even after the unit became operational, Phillips gave Crown Central occasional advice about the technical aspects of the alky-lation process and the operation of the plant. Crown Central, however, was free to reject this advice, for it was the ultimate arbiter of the unit’s operations. Phillips has never owned any part of the unit. Because of its finаl authority over the unit, Crown Central was free to make any alterations that it felt were necessary to the continued profitable operation of the unit, with or without the advice of Phillips. Crown Central did in fact make such modifications, one of which altered the unit’s maximum designed feed temperature and rate. This was done despite Crown Central’s knowledge of the corrosion problems these changes could cause. Crown Central also made changes to the process itself, changes that eventually made the Phillips operating manual obsolete. Phillips claimed that these changes were made without its knowledge or its consent.
In 1978, many years after the unit had become fully operational, Phillips, at Crown Central’s request, sent its employee Harry Bush, an equipment inspector, to help Crown Central conduct an inspection of the alkylation unit. Bush found severe corrosion problems and warned Crown Central that immediate repairs were needed. Afterward, in May 1981, Clyde Archer, a Crown Central inspector, filed a report which stated that one of the feedlines to the unit was dangerously thin and needed replacement. Despite the recommendations of Archer and of Crown Central’s senior maintenance engineer, Crown Central’s management decided not to shut the unit down and repair the pipe.
On June 22, 1981, the unit was shut down for unrеlated repairs, but the corroded feedline was not replaced even though a replacement line was on hand. Around midnight the “stillman” in charge of the unit was ordered to start the unit, but he refused to do so because of its dangerous condition. A Crown Central supervisor was awakened and dispatched to the unit and he ordered the plant started. The still-man complied. A fire broke out a few hours later, and plaintiffs-appellants were injured. Plaintiffs-appellants claimed be *438 low that the excessively thin feeder line caused the fire.
Plaintiffs had previously sought, and received, benefits under the worker’s compensation laws of Texas, following which they filed this diversity suit against Phillips. They sought recovery under products liability, negligence, аnd breach of warranty theories. A jury trial ensued.
The case was submitted to the jury on special interrogatories, the jury’s answers to which comprised the entire verdict. There was no general verdict. Interrogatories one through six were in substance as follows, each calling only for a “yes” or “no” answer:
1. did Phillips supply Crown Central “with a product, the HF Alkylation Process, which was defectively designed and unreasonably dangerous”;
2. conditioned on a “yes” answer to one, whether such product “was a producing cause of the occurrence in question”;
3. was “Phillips ... negligent”;
4. conditioned on a “yes” answer to three, whether such negligence “was a proximate cause of the oсcurrence in question”;
5. did Phillips breach “any implied warranty of fitness for a particular purpose”;
6. conditioned on a “yes” answer to five, whether such breach “was a proximate cause of the occurrence in question.”
The jury answered “no” to each of interrogatories one, three, and five, and, as required by the conditioning instructions stated on the verdict form, did not answer interrogatories two, four, or six. The remaining interrogatories (which concerned contributory negligence on the part of plaintiffs, the comparison of any such to any negligence of Phillips, actual damages, gross negligence on the part of Phillips, and exemplary damagеs) were also all unanswered, as required by the conditioning instructions on the verdict form. The verdict form did not contain any definitions.
Judgment was entered for Phillips on the verdict and this appeal followed.
Appellants now claim that the district court committed reversible error in (1) instructing the jury on “sole cause,” an issue appellants contend is no longer viable in Texas products cases, (2) refusing to instruct the jury about Phillips’ strict liability for “inherently dangerous activities”, and (3) refusing to properly instruct the jury as to Phillips’ contractual duties with Crown Central.
Discussion
I. Sole Cause Instruction
The district court in this case submitted a sole cause instruction, as part of its general charge, which was applicable to all three theories of recovery, negligence, products liability, and breach of warranty. 1 Appel *439 lants objected to this submission, claiming it both contravened the substantive law of Texas and constituted an improper comment on the evidence.
A. Correctness Under the Substantive Law of Texas
We initially note that “[although state law governs the
substance
of the jury instructions, the
manner
of giving instructions is controlled by federal law.”
Martin v. Texaco,
1. Employer Negligence Submissions
Appellants contend that Texas law does not permit the consideration of employer negligence when the employee plaintiff, covered under the Texas worker’s compensation law, seeks recovery from the third party. As appellants note, in
Varela v. American Petrofina Company of Texas, Inc.,
However, neither Varela nor any of its progeny imply, much less hold, that a negligent third party may be liable to an employee plaintiff where the employer’s acts or omissions are the sole cause of the complained of accident and injuries. Here no claim was made by Phillips for contribution or indemnity against Crown Central, and no interrogatory inquired about any negligence, fault, or tort on the part of Crown Central. The comparative fault interrogatory inquired only of the conduct of Phillips and the four appellants; no inquiry was made concerning Crown Central or any third party or third parties. Hence nothing in the charge violated Varela or any principle of Texas substantive law for which it stands.
2. Sole Cause as a Substantive Defense
Appellants next contend that recent Texas Supreme Court decisions eliminate
any
consideration by the jury of sole cause in a suit implicating products liability law,
*440
and thus any submission of sole cause
in any form
is substantive error because sole cause is no longer substantively available in these cases. In
First International Bank in San Antonio v. Roper Corp.,
When a sole cause instruction is submitted in a suit involving both negligence
and
products liability, however, it is uncertain whether Texas courts would consider the submission erroneous.
See
J. Sales,
Product Liability Law in Texas,
¶ 3.04 at 262, esp. n. 247 (1985). In
Gross v. Black & Decker, Inc.,
Moreover, and wholly apart from whether this suit is grounded in negligence or strict products liability, we determine that sole cause is still a valid substantive concept in Texas. Although concededly it is error in Texas courts to give a sole cause instruction in a suit grounded in strict products liability,
see Roper,
In Texas, both negligence and products strict liability suits require causation, although cause in a products strict liability aсtion does not have to be foreseeable to be considered a “producing cause.”
See General Motors Corp. v. Hopkins,
B. Federal Court Instructions on State Law
In diversity actions, federal court jury instructions must accurately describe the applicable state substantive law.
See, e.g., Bass v. International Brotherhood of Boilermakers,
Appellants assert that the district court erred by, in effect, submitting an inferential rebuttal as the controlling issue
*442
in the case. An inferential rebuttal is defined as an issue that seeks to disprove or negate an element of the plaintiffs
prima facie
case.
See, e.g., Scott v. Atchison, Topeka, and Santa Fe Railroаd Co.,
In Texas, inferential rebuttal contentions are not to be presented to the jury in the form of separate special issues, but at the most as explanatory instructions.
See, e.g., Lemos v. Montez,
Appellants place special reliance on
Lewis v. Rego,
We believe that the true nature of appellants’ complaint is that the challenged charge amounted to an improper comment on the weight of the evidence, or an overemphasizing of one party’s contentions. This seems to be the real basis of the decisions in cases such as
Roper.
As previously noted,
Roper
condemned a sole cause instruction stating that it “placed undue emphasis” on that contention and “singled out” and “highlighted” it, but observes that no party “questions the correctness of the instruction” there at issue.
Roper
relied primarily on
Acord,
and
Acord
condemned additional instructions, beyоnd those provided in the Pattern Jury Charges, “however correctly they may state the law.”
However, the rule in federal courts, whether in diversity cases or otherwise, is that the judge has “the power, denied many state judges, to comment on the evidence” and “the power, if he chooses, to summarize the evidence and comment in a proper way on the facts and the evidence if he is careful to make it plain to the jury that they are the sole finder of the facts.” Wright & Miller,
Federal Practice and Procedure: Civil
§ 2557 at 664-65 (footnote omitted). “Federal trial courts have a proper discretion in summarizing and commenting upon the evidence.”
Reyes,
Under these standards, we perceive no error or abuse of discretion in this aspect of the charge. There was no prejudicially unfair emphasis on sole cause — the complained of language is less than two pages in a charge of over thirty pages. The charge as a. whole was not unbalanced or one-sided. That the charge spoke of the specifics which Phillips contended amounted to sole cause is not ground for complaint, as there is no requirement that the charge be abstract. It was made clear to the jury that there could be more than one legal cause of an evеnt. The jury was clearly told that they were the exclusive judge of the facts. There was nothing coercive about the charge, and nothing to indicate to the jury that the judge believed that any acts or omissions of Crown Central were in fact the sole cause of the fire.
Appellants point to the language in the instruction that if the jury found Crown Central’s acts or omissions were the sole cause of the fire, “your verdict should be for the defendant.” While this told the jury the legal effect of a sole cause determination on their part, that does not render the instruction erroneous. Federal judges are free to tell the juries the effects of their answers.
See, e.g., Martin,
Finally, we think any possible error was harmless. While the reference to a verdict for defendant, if Crown Central’s acts or omissions were determined to be the sole cause, was inexact, since there was no verdict form allowing a verdict for either party as such, it was clear from the charge that the sole cause claim relatеd to the question of cause. That was the subject matter of the instruction in question. In reviewing the charge, “we ignore technical imperfections.”
Pierce v. Ramsey Winch Co.,
Accordingly, we reject appellants’ argument based on the sole cause instruction.
II. Inherently Dangerous Activities
Appellants next contend that the district court erred in not instructing the jury on Phillips’ strict liability for “inherently dangerous activities,” a theory of recovery under Texas law. Texas courts have endorsed the position of the
Restatement (Second) of Torts
§ 414 (1965), and imposed liability on principals who attempt to farm out inherently dangerous activities to independent contractors.
See Sun Pipeline Co., Inc. v. Kirkpatrick,
In Texas, vicarious liability is imposed on an employer for the acts of an independent contractor conducting inherently dangerous activities on behalf of the employer. Here, however, there is no employer-independent contractor relationship. An independent contractor is one who performs an activity for another, yet attains functional autonomy over his actions.
Pitchfork Land and Cattle Co. v. King,
Crown Central cannot be labeled an independent contractor because, quite simply, Crown Central did not work for Phillips. It is apparent that Crown Central acted only for itself, and that Crown Central, and only Crown Central, called the shots. The contract between Phillips and Crown Central was for the sale and lease of certain knowledge and technology, including patents. This agreement did not make Phillips the employer of Crown Central, nor did it make Crown Central an independent contractor.
Because there is no independent contractor-employer relationship, we hold that the district court’s action in not presenting this theory to the jury was correct. Thus, we need not decide whether the activities involved here are intrinsically dangerous or whether appellants, as employees of an independent contractor, can recover. 6
III. Implied Duties
Appellants’ last contention is that the district court committed error in not submitting two theories on the basis of which appellants claim that Phillips owed them implied duties. First, appellants claim that since Phillips was contractually bound to perform certain tasks, Phillips had a duty to perform these tasks with reasonable care.
See
Prosser and Keeton,
The Law on Torts,
§ 93 at 670 (5th ed. 1984). Second, appellants claim that regardless of whether Phillips was contractually bound to perform a task, once Phillips undertook to perform it had a duty in tort to do so with reasonable care.
See Colonial Savings Association v. Taylor,
It is precisely because these theories are grounded in fault that we find that the district court’s failure to separately submit these two issues was not an abuse of discretiоn, for such a submission was otherwise adequately covered by the charge. The district court submitted negligence to the jury as one of three theories of recovery, and the negligence instruction subsumed the two “implied duty” theories.
7
*446
As we have stated, “[A] trial court is not required , to give every charge requested .;. if the subject matter of such requested instructions was sufficiently covered by other instructions from the court.”
Rehler, 777
F.2d at 1078.
See also, e.g., Trinity Carton Co. v. Falstaff Brewing Co.,
Conclusion
Having concluded that none of appеllants’ contentions present reversible error, the judgment of the district court is affirmed.
AFFIRMED.
Notes
. The district court instructed the jury as follows:
"In addition to its other defense claims, defendant alleges that the acts or omissions of Crown Central Petroleum Corporation were the sole cause of the explosion, fire or resultant injuries to plaintiffs. In that regard you are instructed that there may be more than one cause of an occurrence, but there can only be one sole cause. If an act or omission of any person not a party to the suit was the sole cause of the occurrence, then no act, omission, or product of any party to the suit could have been a cause of the оccurrence.
"Specifically, defendant claims that Crown Central Petroleum Corporation’s acts or omissions were the sole cause of the occurrence in question in the following particulars:
"1. Crown Central Petroleum Corporation, acting on its own, has made substantial and significant modifications to the unit.
"2. Crown Central Petroleum Corporation has not been operating the HF Alky Unit No. 1 in accordance with the Operating Manual for that unit furnished by Phillips in 1964.
"3. Crown Central Petroleum Corporation knew for many years that it was experiencing severe corrosion problems in the feed area of the HF Alky Unit No. 1 and knew that this feedline was dangerously thin due to internal cоrrosion prior to the fire on June 23, 1981. Despite this knowledge and the knowledge that the feedline should be replaced, Crown Central Petroleum Corporation decided to continue to operate the unit with the feedline in such condition;
"4. Crown Central Petroleum Corporation started up the unit prior to the occurrence in *439 question although Crown Central Petroleum Corporation management was advised some four hours prior to the fire that the unit was in a dangerous condition and should not be started up.
"You are instructed that if you should find that the acts or omissions of Crown Central Petroleum Corporation were the sole cause of the fire and resultant injuries to plaintiffs, then your verdict should be for the defendant.
Sole cause applies to all three theories of law as asserted by plaintiffs."
As appellants observed, this instruction is more than the standard, general definitional sole cause instruction requested by appellee, for it refers to Phillips’ assertions of particular matters as being claimed to constitute sole cause. This instruction was not submitted as a part of the verdict form, but rather as a part of the court’s general charge.
. We do not regard the special situation presented in
Huerta v. Hotel Dieu Hospital, 636
S.W.2d 208 (Tex.App.—El Paso),
aff’d,
. In Texas, the Texas Pattern Jury Charges are approved as a correct statement of the state’s substantive law.
Acord,
”[I]t is scarcely error per se [for a federal judge] to decline to follow pattern or form book instructions. Nor does Erie compel the use of pattern state instructions, since the manner of giving jury instructions is controlled by federal law, ... and a pattern charge is but one procedure for instructing the jury — other procedures may be used so long as they correctly describe the applicable state law____ Pattern instructions are merely some evidence that an instruction is advisable.” Chemetron,682 F.2d at 1178 (citations omitted).
The obligation of the district judge was only to correctly charge the jury on the Texas substantive law, and further state court irestrictions or limitations on the charge do not apply.
. Appellants also claim that
Gonzales
is a condemnation of all sole cause submissions. However,
Gonzales
was concerned with a district court's denying appellants’
requested, interrogatory
on sole cause.
. However, not all mention of sole cause in the charge leads to reversal in Texas courts.
See, e.g.. Woods v. Cane Carrier Co., Inc.,
. We also note that even if Crown Central was an independent contractor and this work was "inherently dangerous," liability would not be imposed on Phillips if Crown Central had sole control of the process.
See Shell Oil Co. v. Waxler,
. On the contractual implied duty claim, appellants' counsel alleged that there was a “legal duty accompanying each contract to perform with due care, skill, and reasonable expedience and faithfulness the thing or things agreed upon to be done.” These "things" included the exchange of technical information, the rights of Phillips to inspect the plant, and Phillips’ duty to provide advisory services to Crown Central. Appellants argue that once Phillips undertook to complete an inspection, it promised to do so with reasonable care.
The jury below was charged on Phillips' negligence, and this instruction included a potential lack of reasonable care on Phillips’ part due, inter alia, to its failure to insрect or properly inspect the plant, to notify Crown Central of excessive corrosion, and to warn Crown Central of the danger of possible revision in the process. Moreover, ordinary care was defined in the charge as “that care which reasonably prudent persons exercise in the management of their own affairs____” (Emphasis added.) We find it apparent that appellants’ two implied duty theories were redundant because the instructions and special issues actually submitted completely encompassed the duties and issues that appel *446 lants were asserting. Moreover, the district judge listed ten separate events which could constitute negligence by Phillips, and these events thoroughly overlap with appellants’ desired submissions.
