Opinion Per Curiam.
Appellants Edward William Hull and Shirley Hull filed this products liability action against Eaton Corporation (Eaton) and Yale Industrial Trucks Baltimore-Washington, Inc. (YIT), 1 seeking damages for injuries sustained by Mr. Hull while operating a forklift manufactured by Eaton and sold by YIT to Hull’s employer, Giant Foods, Inc. (“Giant”). 2 The Travelers Insurance Company, the carrier for Hull’s worker’s compensation claim, intervened. After the Hulls failed to identify their intended expert witness pursuant to Eaton’s discovery request and the court’s order, the district court imposed a sanction precluding the plaintiffs from introducing expert testimony. Subsequently, the court granted Eaton’s motion for summary judgment, holding that (1) the plaintiffs would be unable to make out a case of products liability without expert testimony; (2) the plaintiffs’ breach of warranty claim was barred by the statute of limitations; and (3) Eaton could not be held liable for the wrongful acts of YIT.
I.
On January 14, 1981, Mr. Hull was operating forklift number 501 at Giant’s Land-over, Maryland warehouse. The forklift is equipped with a counterweight which enables it to lift heavy loads. The counterweight sits on two, hooks extending from the frame, and is further attached by three bolts which are threaded into the backside of the counterweight from the frame. The heads of the bolts are countersunk into the frame and covered by the battery. When the counterweight is properly installed, the bolts stabilize it and prevent it from moving horizontally or vertically and disengaging from the mounting hooks. At the time of the accident these three bolts were not in place. Thus, the hooks were all that secured the counterweight to the frame of the forklift. As Hull was driving the forklift through the warehouse area, he hit a bump which caused the left front end of the forklift to dip. When the front end of the forklift dipped, the counterweight slipped off the hooks and fell to the ground, causing an overhead guard which was attached to the counterweight to fall on Hull and injure him.
Eaton manufactured the forklift and delivered it to YIT in December, 1977. The forklift was originally equipped with a counterweight that gave it a 2500 pound carrying capacity. Sometime after delivery to YIT, the original counterweight was replaced with a heavier counterweight that increased the forklift’s lifting capacity to 3000 pounds. Giant purchased the forklift from YIT in February, 1978, and YIT informed Eaton of the changed counterweight late that month.
The Hulls’ complaint sets forth claims for relief based on strict liability in tort, negligence, failure to warn, and breach of express and implied warranties. The common theory underlying each claim is that if the counterweight had been properly attached to the frame with the three bolts, the accident would not have happened. The strict liability claim asserts that Eaton’s design of the forklift was defective because the bolts were removable and the operator could not determine by casual inspection if the counterweight was properly attached. Under the negligence claim, Eaton’s manufacture and sale of the forklift with concealed and removable bolts breached a duty of care owed to the Hulls. The failure to warn claim is based on the allegation that Eaton had a duty to warn of the special dangers that resulted from the de *451 sign of the forklift. Finally, according to the warranty claim, Eaton breached a contractual obligation to deliver the forklift in merchantable condition. Subsequent to filing their complaint, the Hulls raised even an additional claim — that Eaton was vicariously liable for YIT’s negligent installation of the replacement counterweight.
On April 21, 1983, Eaton filed interrogatories, including one that requested the identity, qualifications, and expected testimony of the plaintiff’s expert witnesses. Almost eight months passed without an answer to that interrogatory, and Eaton obtained an order from a magistrate compelling the plaintiffs to respond by January 16, 1984. Plaintiffs then filed a “supplemental answer” refusing to name an expert on the grounds that they had not obtained sufficient information from Eaton concerning sales of forklifts of the type involved in the accident. Thereafter, Eaton filed a motion to sanction the plaintiffs under Federal Rule of Civil Procedure 37. Subsequent to a June 11, 1984 hearing at which the plaintiffs again refused to answer the interrogatory, the magistrate granted the sanctions motion and entered an order precluding the plaintiffs from presenting expert testimony at trial on the liability issue. The district judge held a hearing on October 5, 1984, and — the plaintiffs still refusing to name their expert witness — entered an order affirming the magistrate’s sanction.
The district court granted Eaton’s motion for summary judgment on November 21, 1984. The court held that the critical facts in the strict liability, negligence, and failure to warn claims were the risks, costs and benefits of alternative designs of the forklift, and that determination of these facts required expert testimony. Because the plaintiffs could not introduce expert testimony as a result of the discovery sanction, the district court, held that they were unable to make out essential elements of these claims. In addition, the court held that the plaintiffs’ breach of warranty claim was barred by a four year statute of limitations, and that the relationship between Eaton and YIT was not such that Eaton could be held vicariously liable for YIT’s negligent installation of the replacement counterweight.
On appeal the Hulls contend that there are genuine issues of material fact and that the district court’s holding on each of the claims was erroneous. They argue that (1) they had no need to produce an expert witness, because the district court erred as to the necessary elements of strict liability, negligence and failure to warn claims, and because they offered evidence showing the existence of a prior alternative design of the forklift; (2) the court should have applied the “discovery rule” to determine when the statute of limitations began to run on the breach of warranty claim; and (3) the record contains sufficient facts to establish a genuine issue as to whether Eaton is vicariously liable for the tortious acts of YIT. In addition, Travelers — but not the Hulls — argues that the discovery sanction was improper.
II.
We first consider the argument that the district court erred in imposing the discovery sanction under Federal Rule of Civil Procedure 37. 3 Travelers contends that where, as here, a sanction precluding plaintiffs from presenting certain evidence at trial is combined with a district court holding on summary judgment that without that evidence the case must be dismissed, the discovery sanction becomes in effect a *452 dismissal of the case. Since appellants were never warned by the district judge that their failure to name an expert witness would lead to de facto dismissal of their case, it is argued, the sanction was so harsh as to constitute an abuse of discretion. We disagree.
The determination of an appropriate discovery sanction is left to the discretion of the trial court.
National Hockey League v. Metropolitan Hockey Club, Inc.,
We reject the argument that the district court abused its discretion by failing to consider the practical effect its sanction order would have on appellants’ case, even assuming the effect could have been discerned at the time the sanction was imposed.
4
A judge can certainly impose a $10,000 sanction on a party whose discovery violation causes his opponent $10,-000 in added expenses without inquiring whether the violator can afford to pay the fine. So too, we believe, can a judge sanction a party's continued and unexcused refusal to name an expert witness by precluding testimony from any such witness without first determining how badly the party needs the witness. Rule 37(b)(2)(B) explicitly authorizes the court to prohibit a party who fails to obey a discovery order from introducing designated matters in evidence. In light of appellants’ representations to the magistrate that they did not even intend to use an expert witness, such a sanction seems eminently reasonable.
5
District judges face great difficulties in controlling discovery procedures — which, all too often, are abused by one side or the other.
See, e.g., Perkinson v. Gilbert/Robinson, Inc.,
III.
A.
Summary judgment is warranted where “the pleadings, depositions, answers to interrogatories, and admissions on file, together with the affidavits, if any, show that there is no genuine issue as to any material fact and that the moving party is entitled to summary judgment as a matter of law.” Fed.R.Civ.P. 56(c). We review the record in the light most favorable to the nonmoving party.
Tymshare, Inc. v. Covell,
[T]he plain language of Rule 56(c) mandates the entry of summary judgment, after adequate time for discovery and upon motion, against a party who fails to *453 make a showing sufficient to establish the existence of an element essential to that party’s case, and on which the party will bear the burden of proof at trial. In such a situation, there can be no “genuine issue as to any material fact,” since a complete failure of proof concerning an essential element of the nonmoving party’s case necessarily renders all other facts immaterial.
Thus, if appellants were unable to establish essential elements of their negligence, strict liability and failure to warn claims without offering expert testimony — as the district court held 6 — or some additional evidence, summary judgment was properly granted on those claims.
We discuss in turn the necessary elements of each claim under District of Columbia law.
7
We have scant difficulty disposing of appellants’ challenge to the district court’s holding on the proper makeup of a negligence claim. A manufacturer is liable in negligence for damage caused by his product if he fails to exercise reasonable care in its design.
Westinghouse Elec. Corp. v. Nutt,
Appellants raise more substantial questions regarding the elements of their strict liability claim. Relying, to be sure, on section 402A of the Restatement (Second) of Torts,
8
the district court held that to establish strict liability for defective design under D.C. law, the Hulls needed, again, to show the risks, costs and benefits of the product in question and alternative designs. We note at the outset that there is no District of Columbia case clearly setting out the necessary elements of a D.C. strict liability claim.
Compare Fisher v. Sibley Memorial Hospital,
Finally, with regard to the failure to warn claim, the district court held that appellants needed to show “the basis for determinations of dangerousness and the anticipated likelihood of injury by the product.” The Hulls disagree, arguing that the adequacy of a warning is almost always a question for a jury. Appellants are correct as far as they go.
See Payne,
B.
Having determined the district court correctly set out elements of the negligence, strict liability and failure to warn claims, we now discuss whether appellants offered sufficient evidence to create a genuine issue of fact as to those elements. The district court granted summary judgment because appellants lacked expert testimony on the dangers of the forklift and the consequences and trade-offs of alternative designs. We agree, of course, that with respect to some matters expert testimony is more than advantageous — it is required.
See Simpson v. Chesapeake & Potomac Tel. Co.,
First, the Hulls point to the undisputed fact that Mr. Hull’s accident occurred. Unfortunate as it was, however, the accident alone reveals neither whether the accident was foreseeable, nor the likelihood that the risk would manifest itself, nor whether the risk outweighed the costs of avoiding it. Second, the Hulls established that Eaton manufactured a previous forklift model, the K-58, on which the counterweight bolts were plainly visible. The Hulls argue, as we noted, that visible bolts make accidents such as the one that befell Mr. Hull less likely to occur. But evidence that one alternative design was technically feasible, and perhaps safer, proves nothing with regard to the actual risk of the chosen design, nor the relative utilities of the alternative designs, nor the costs involved in adopting one design over the other. “[Ejvidence of a design alternative, by itself, is not sufficient to impose liability on the manufacturer.”
Westinghouse Elec. Corp. v. Nutt,
C.
Although the district court held that the absence of expert testimony was fatal
*456
to the plaintiffs’ breach of warranty claim, it also held that this claim was barred by the statute of limitations.
See supra
note 6. The parties agree that the statute of limitations is four years under both District of Columbia and Maryland law, as provided in Uniform Commercial Code § 2-725.
See
D.C.Code Ann. § 28:2-725; Md.Com.Law Code Ann. § 2-725.
11
The disagreement concerns the point at which the statute of limitations began to run. Giant purchased the forklift from YIT in February, 1978. Hull’s accident occurred on January 14, 1980. Appellants filed their complaint on January 13,1983, approximately four years and ten months after Giant took delivery of the forklift. The district court held that, under District of Columbia law, the plaintiffs’ cause of action accrued when the breach of warranty took place — in February, 1978, when YIT delivered the forklift to Giant. Appellants argue, instead, that Maryland law governs the warranty claim, and that Maryland applies the “discovery rule” — under which a cause of action accrues when the plaintiff knows or reasonably should know of his injury. Assuming
arguendo
that Maryland law governs appellants’ substantive claim,
see supra
note 7, we believe nonetheless that the district court correctly applied the District of Columbia statute of limitations. The district court, as a federal court sitting in a diversity case, was required to look to state law for the applicable statute of limitations.
Guaranty Trust Co. v. York,
The Hulls contend in the alternative that even under the District of Columbia statute of limitations the discovery rule applies to a claim for breach of contract under the U.C.C. Appellants cite a recent case in which the District of Columbia Court of Appeals applied the discovery rule to “an action based upon tort and contract claims arising out of allegedly deficient design and construction of an addition to a house.”
Ehrenhaft v. Malcom Price, Inc.,
IV.
Finally, the Hulls contend that the district court erred in dismissing their claim that Eaton was vicariously liable for YIT’s negligent installation of the 3000 pound counterweight. 13 The district court examined the Dealer Selling Agreement between Eaton and YIT to determine whether it indicated an agency relationship. Although the agreement required YIT to provide service on Eaton forklifts, to advertise itself as a dealer of Eaton’s products, to furnish information, and'to conform to any business standards recommended by Eaton, 14 the court found that nothing in the agreement or in any other evidence that suggested day-to-day control of YIT’s operation. It found that such control was essential, however, if Eaton was to be held vicariously liable.
We think that the district court was correct. In
Quijada Corp. v. General Motors Corp.,
Appellants rely on
Caporale v. Raleigh Industries of America, Inc.,
V.
We conclude that (1) the district court did not abuse its discretion in imposing the discovery sanction; (2) the court properly granted summary judgment because without additional evidence the Hulls were unable to establish a case of negligence, strict liability or failure to warn; (3) the court properly refused to apply the “discovery rule” to the breach of warranty claim; and (4) Eaton cannot be held liable for the acts of YIT. Accordingly, the judgment of the district court is
Affirmed.
Notes
. Although YIT was originally named as a defendant, it was never served with process; nor did it ever appear as a defendant. Apparently it went into bankruptcy sometime before the plaintiffs commenced this action.
. The case was originally filed in District of Columbia Superior Court, but was removed to federal district court for the District of Columbia.
. Rule 37(b)(2) provides in pertinent part-as. follows:
If a party ... fails to obey an order to provide or permit discovery ... the court in which the action is pending may make such orders in regard to the failure as are just, and among others the following:
(B) An order refusing to allow the disobedient party to support or oppose designated claims or defenses, or prohibiting him from introducing designated matters in evidence; (C) An order striking out pleadings or parts thereof, or staying further proceedings until the order is obeyed, or dismissing the action or proceeding or any part thereof, or rendering a judgment by default against the disobedient party.
. It’s not always clear what effect certain rulings will have on the ultimate outcome of a case, especially in an area of law so unsettled as products liability. Here, the discovery sanction was entered on October 16, 1984, while summary judgment was not granted until November 21, over a month later. Travelers would apparently have us require the district judge to have decided the motion for summary judgment before deciding the sanctions motion — unless he could have predicted, accurately, the impact of the sanction.
.
United States v. Sumitomo Marine & Fire Ins. Co.,
. The district court held that the plaintiffs’ inability to present expert testimony mandated summary judgment on the breach of warranty claim as well, but the court included an alternative holding based on the statute of limitations. Because we agree that the breach of warranty claim is barred by the statute of limitations, see infra pp. 455-457, we do not determine the need for additional evidence on this claim.
. The Hulls’ complaint alleged Maryland law governed this case, but their opposition to the summary judgment motion relied upon District of Columbia law, and the district court decided the case on that basis. Only in the motion for reconsideration did the Hulls return, tentatively, to their original position — that "Maryland law would most probably apply" — and then only with respect to the warranty claim. On appeal, there is no disagreement that District of Columbia law governs the other claims.
.Section 402A provides, in pertinent part, that one who
sells any product in a defective condition unreasonably dangerous to the user or consumer ... is subject to liability for physical harm thereby caused to the ultimate user ... if (a) the seller is engaged in the business of selling such a product, and (b) it is expected to and does reach the user or consumer without substantial change in the condition in which it is sold.
Restatement (Second) of Torts § 402A (1965).
. "The views of a district judge [in a diversity case] who is a resident of the state where the controversy arose interpretive of the state’s laws, carry extraordinary force on appeal where there are no state decisions directly on point or none which provide a clear precedent.”
Rasmussen Drilling, Inc. v. Kerr-McGee Nuclear Corp.,
. The court in
Payne
relied on a factually-similar previous case to establish that the particular risk gave rise to a duty to warn.
Payne,
. Section 2-725 provides in relevant part:
(1) An action for breach of any contract for sale must be commenced within four years after the cause of action has accrued....
(2) A cause of action accrues when the breach occurs, regardless of the aggrieved party’s lack of knowledge of the breach. A breach of warranty occurs when tender of delivery is made, except where a warranty explicitly extends to future performance of the goods and discovery of the breach must await the time of such performance the cause of action accrues when the breach is or should have been discovered.
Appellants do not claim that the alleged warranty explicitly extended to future performance.
. The Ehrenhaft court did not consider warranties arising under the Uniform Commercial Code.
. .The Hulls argue that there is a factual issue as to who installed the 3000 pound counterweight. There seems to be no dispute, however, that when Eaton delivered the forklift to YIT in December, 1977, it had a 2500 pound counterweight. The evidence appellants cite — (1) YIT’s December 28, 1977 letter to Giant, and accompanying documents, offering to sell the forklift; (2) YTTs February 16, 1978 "Unit Transfer Form,” which recorded YIT’s delivery of the forklift to Giant; and (3) YIT’s February 28, 1978 request to Eaton for a new capacity plate to reflect an increase in lifting capacity to 3000 pounds — creates an issue only as to whether it was YIT or Giant that changed the counterweight. Plaintiffs do not argue an agency relationship between Eaton and Giant. Accordingly, we interpret the record most favorably to plaintiffs and assume YIT installed the new counterweight.
. The Dealer Selling Agreement between YIT and Eaton states:
To be in good standing, an authorized [Eaton] dealership shall:
g. adopt and appropriately apply objective standards of business procedure, operation and administrative practice recommended by [Eaton] for application to all authorized [Eaton] dealerships (such standards will be based on objective periodic evaluation of the operations, and operating results of authorized [Eaton] dealers as a group, and will be published from time to time in a Dealer Operations and Policy Manual).
The standards themselves are not contained in the record, but the affidavit of YIT’s service manager, Charles L. Poole, gives some indication of their content in stating, "There were no mandatory requirements set forth by Eaton to govern the way that the dealership was run. Service or operations manuals contained guidelines, but we were not obligated to follow those suggestions.”
