LEWIS R. MORGAN, Circuit Judge:

Russell Walters, Alton Cavenaugh, J. L. Henson and E. L. Lanterman, individually and as representatives of a class composed of over-the-road-relay drivers, brought the present action against Roadway Express, the International Brotherhood of Teamsters, and Local 891 of that union. The instant dispute involves the following sequence of events. On January 3, 1970, the Interstate Commerce Commission [hereinafter ICC] granted Roadway permanent authority to control West Brothers, Inc. [West], a Mississippi motor carrier in desperate financial condition, and Roadway merged the operation of West into its system. Shortly thereafter, Roadway transferred twenty-nine West drivers from various other terminals to the Roadway terminal in Meridian, Mississippi. In determining the seniority of these transferring employees, Roadway had two options: it could either "dovetail" the employees — a term used to refer to a merging of two separate seniority lists upon the transfer of employees of a company from one terminal to another — or place the names of the West drivers at the bottom of the existing seniority list at the Meridian terminal. Roadway submitted the question to the Change of Operations Committee, a sub-committee of the Southern States Multi-Conference Committee that is composed equally of union and management officials not affected by the change in question. Following a hearing, that body ruled that the seniority of transferred drivers should be dovetailed with that of those drivers already employed at the Meridian terminal; that is the seniority of the former was to be based on the date of their employment with West, not on the date of their transfer to Meridian. This decision resulted in a reduction of seniority for the plaintiffs, who represent drivers who were working at the Meridian terminal before the transfer of West drivers. Earl Byers, one of these Roadway employees whose seniority was being reduced, filed a grievance that was heard by the Southern States Multi-Conference Committee pursuant to the grievance procedure outlined in the collective bargaining agreement. Art. 7, p. 59. That committee denied the protest.

Subsequently, on April 10-12, 1970 several employees allegedly engaged in an unauthorized work stoppage to protest the reduction in their seniority. Roadway discharged eight of them, pursuant to Article 42, Section 2, p. 100-101 of the collective bargaining agreement. These eight filed a grievance with the appropriate committee; the grievance committee reinstated three of the grievants without pay, but upheld the discharges of the other five.

On this appeal, plaintiffs raise three issues. First, they contend that the reduction in their seniority violated the order of the ICC granting Roadway control over West's operations. Second, they argue that this reduction violated the National Master Freight Agreement [NMFA], the collective bargaining agreement under which the unions and management were governed. Finally, plaintiffs contend that the committee erred in denying the plaintiffs' grievance over their dismissal for allegedly conducting a wildcat strike.

The district court rendered a judgment for defendants as a matter of law on the ICC claim, holding that any complaint relating to an alleged violation of an ICC order was within that agency's exclusive jurisdiction. Accordingly, the district court ruled that it had no jurisdiction over the claim and granted a partial summary judgment for defendants. We disagree with that court's conclusion since 28 U.S.C. § 1336 provides that the district court shall have jurisdiction to enforce, in whole or part, any order of the Interstate Commerce Commission. Here, plaintiffs allege that the committee's action in reducing their seniority violated a condition in the ICC order of merger — that no employee be placed in a worse position as a result of the merger — and, thus, they seek enforcement of that order as part of their claim for relief. § 1336 is, therefore, a jurisdictional basis for this part of the complaint. See Clemens v. Central R.R. Co. of New Jersey, 264 F. Supp. 551 (E.D.Pa. 1967), reversed on another ground, 399 F.2d 825 (3rd Cir. 1968). We offer no opinion as to the plaintiffs' likelihood of success in their litigation of this claim, but merely hold that it should not have been dismissed on jurisdictional grounds.

Plaintiffs' second and third contentions, jurisdiction of which is § 301 of the Labor Management Relations Act, 29 U.S.C. § 185 (1973), relate to the propriety of the committee's decision, made pursuant to the collective bargaining agreement, to reduce their seniority and to discharge five of their members for their alleged participation in a wildcat strike. First, they argue that the joint committee of union and management officials exceeded its authority under the agreement when it allowed the seniority of transferring West drivers to be merged with their own. The United States Supreme Court has held that reviewing courts are to accord the same finality to decisions of committees operating under the National Master Freight Agreement as they do to traditionally neutral arbitrators. Riss Co. v. General Drivers Local 89, 372 U.S. 517, 83 S.Ct. 789, 9 L.Ed.2d 918 (1963). That courts have a very limited role in reviewing the merits of an arbitrator's decision is a familiar axiom in labor law. Thus, the reviewing court asks only whether the particular grievance is arbitrable under the agreement and whether the arbitrator's award "draws its essence from the [contract]." United Steelworkers v. Enterprise Wheel and Car Corp., 363 U.S. 593, 597, 80 S.Ct. 1358, 1361, 4 L.Ed.2d 1424 (1960). Assuming that the court can answer both these questions affirmatively, the court's participation in determining the correctness of the arbitrator's decision is over, for "plenary review by a court of the merits would make meaningless the provision that the arbitrator's decision is final . . .; it is the arbitrator's [decision that] was bargained for and [as] far as the arbitrator's decision concerns construction of the contract, the courts have no business overruling him because their interpretation of the contract is different from his." Id. at 599, 80 S.Ct. at 1362. See also U.S. Steelworkers v. Warrior and Gulf Navigation Co., 363 U.S. 574, 80 S.Ct. 1347, 4 L.Ed.2d 1409 (1960); Gulf States Telephone Co. v. Local 1692, 416 F.2d 198 (5th Cir. 1969); Brotherhood of RR Trainmen v. Central of Ga. Railway Co., 415 F.2d 403 (5th Cir. 1969); Safeway Stores v. American Bakery Confectionary Workers Local 111, 390 F.2d 79 (5th Cir. 1968).

In this case, plaintiffs have not denied that seniority claims are arbitrable under the collective bargaining agreement, but they do contend that the COC went beyond the scope of the agreement when it reduced plaintiffs seniority. Specifically, plaintiffs point to § 3(a)(1)-(5) and § 5(b)(2). of Article 5 of the NMFA, which sets out guidelines to be used in determining seniority questions, and argue that these provisions required the COC to place West drivers at the bottom of any seniority list. Assuming without deciding that these provisions accurately describe the circumstances under which the West-Roadway merger occurred, we find that plaintiffs have ignored the crucial section of Article 5 — § 7 — which states:

The parties acknowledge that specific situations may arise which may not be covered by the rules set forth in this Article or in which the parties may feel that different treatment of the problem is necessary. In such situation, the Employer, the Unions involved, and the Area Multi-Conference or National Committees may mutually agree to such disposition of the seniority problems as in their judgment is appropriate under the circumstances. The Change of Operations Committee under the Local Supplements or the National Master Agreement shall have the authority to add to or to modify these rules in specific situations presented to them. (Emphasis added.)

Thus, § 7 makes it clear that § 3 and § 5 are merely guidelines that the parties can decline to employ when they feel that such use is inappropriate. Indeed, the Third Circuit encountered a situation almost identical to the present case and held that § 7 permitted the joint committee to fashion appropriate seniority allocations:

But Section 7 leaves flexibility to deal with unforeseen situations, permitting the parties to the contract to bargain further on an ad hoc basis whenever a closing occurs. The parties reserved the right to have the employer, the unions involved and specially designated committees `mutually agree' at some future time to a disposition of the seniority problems as they may determine in their best judgment. Section 5(b)(2) was the rule but in specific situations Section 7 retained the right of the aforementioned parties to find other flexible solutions. They thereby retained their freedom to continue their contract making during the term of the pact. Thus, seniority rights of individual employees under the contract in the event of a closing of a terminal, were subject to further negotiations and agreement under Section 7.

The actions of the membership and the past history of the contract supports this rationale. While it seems that all local officials to whom transferees from Bedford spoke expected Section 5(b)(2) to be adhered to, it is equally clear that the matter was not settled. There was a considerable amount of discussion at each committee meeting about whether the men should be dovetailed or put at the bottom of the seniority list at their new terminal. There is nothing in the record that would lead to the conclusion that such discussions were out of the ordinary, or that the expectation of anyone involved in the proceedings was that the matter was totally concluded by automatic application of Section 5(b)(2).

Price v. International Brotherhood of Teamsters, 457 F.2d 605, 611 (3rd Cir. 1972). See also Bieski v. Eastern Automobile Forwarding Co., 396 F.2d 32 (3rd Cir. 1968); McDermott v. Teamsters Joint Council No. 53, 347 F. Supp. 473 (E.D.Pa. 1972); Albert v. Chemical Leaman Tank Lines, 344 F. Supp. 1141 (S.D.W.Va. 1972).

Having determined that the joint committee acted within the confines of the NMFA in reducing plaintiffs' seniority, however, does not end the inquiry. Thus, if plaintiffs can demonstrate that they were not awarded fair representation by their union in pursuing their claims on seniority, the decision of the joint committee is not deemed final. Hines v. Anchor Motor Freight, Inc., 424 U.S. 554, 96 S.Ct. 1048, 47 L.Ed.2d 231 (1976). The well-settled guideline for determining whether the union did not fairly represent its members' claims was articulated by the Supreme Court in Vaca v. Sipes, 386 U.S. 171, 87 S.Ct. 903, 17 L.Ed.2d 842 (1967). In that case, the Court held that a union has an obligation to "serve the interests of all members without hostility or discrimination toward any, to exercise its discretion with complete good faith and honesty, and to avoid arbitrary conduct." 380 U.S. at 177, 87 S.Ct. at 910, 17 L.Ed.2d 850. In this case, the district court found that the local union had satisfied this "good faith" test and plaintiffs have not demonstrated to us that this finding is clearly erroneous under F.R.Civ.P. 52(a).

Finally, plaintiffs challenge the joint committee's finding that five of their number were properly discharged for engaging in a wildcat strike. Yet, Roadway contends that Article 42, § 2 authorized the discharges and that the Multi-State Grievance Committee resolved the grievances filed by the five employees in its favor. We agree with the district court's finding that the local union fairly represented the discharged employees in their hearing on the grievance, pursuant to Vaca, and, therefore, no arbitrary or bad faith conduct existing on the part of the union, we do not inquire into the reasoning of the grievance committee — the body designated contractually by the parties to make a final decision in such matters.

Finally, appellee Roadway argues that the trial court abused its discretion in requiring it, the prevailing party, to bear its own costs. Rule 54(d) of the Federal Rules of Civil Procedure provides that "costs shall be allowed as of course to the prevailing party unless the court otherwise directs." The trial court has broad discretionary powers in taxing costs, but its decision may be overturned if it abuses that discretion. Harrington v. Texaco, Inc., 339 F.2d 814 (5th Cir. 1964), cert. denied, 381 U.S. 915, 85 S.Ct. 1538, 14 L.Ed.2d 435. While the rule does not prevent a trial court from requiring a prevailing party to bear its own costs, "the language of the rule reasonably bears the intendment that the prevailing party is prima facie entitled to costs and it is incumbent on the losing party to overcome that presumption . . . [since] denial of costs . . . is in the nature of a penalty for some defection on his part in the course of the litigation." Popeil Brothers v. Schick Electric, Inc., 516 F.2d 772, at 775 (7th Cir. 1975). Accordingly, when a trial court exacts such a penalty, it should state reasons for its decision. Id. Accord, Pelineon de Navegacion v. Texas Petroleum Co., 540 F.2d 53 (2 Cir. 1976); Samuel v. University of Pittsburg, 538 F.2d 991 (3rd Cir. 1976); ADM Corp. v. Speedmaster Packaging Corp., 525 F.2d 662 (3rd Cir. 1975). Here, the trial court gave no reasons for its decision to deny the prevailing parties their cost. Accordingly, we remand the question of costs to the district court for it to state a justification for its denial of costs to appellees, so that we may have some basis upon which to judge whether it acted within the proper confines of its discretion.

In summary, we remand the matter of costs and that part of the complaint seeking enforcement of the ICC order to the district court and affirm its approval of the committees' decisions on seniority and the discharges of five employees.

Affirmed in part, reversed in part.