opinion: PHILLIPS, Chief Judge.
  This is a suit to compel arbitration. The District Court refused to order arbitration, rendering judgment in favor of the appellee employer, Boyd G. Hem-inger, Inc. The three labor unions appeal. Although Frank Fulton, Inc. also was a party to this litigation in the District Court, the unions, in this appeal, seek only a remand for direction of arbitration with Heminger. Jurisdiction is founded on § 301 of the Labor Management Relations Act, as amended. 29 U. S.C. § 185. We reverse and remand.
  Each of the three unions is party to individual collective bargaining agreements with the Heminger corporation, which is in the construction industry. The bricklayers’ agreement requires that seventy per cent of all the employer’s bricklayers must be union members, if they are available and competent. The carpenters’ agreement requires that all unemployed carpenters in a four-county area in and around Canton, Ohio, be hired before any outside help is employed. The Ironworkers’ agreement provides that other than a minimum of key employees, all of Heminger’s iron-workers shall be furnished by the union.
  The unions allege that Heminger violated each of these union security provisions by creating a sham corporation (appellee Frank Fulton, Inc.) to operate with non-union employees in the geographical areas covered by the agreements. A demand for arbitration for breach of the above provisions was made by each union on June 14, 1972. This suit was instituted after Heminger refused to arbitrate.
  The bricklayers’ arbitration agreement provides that the arbitration procedure will be used to settle “any disputes occurring during life of this Agreement in a peaceful manner .” The carpenters’ arbitration agreement provides for arbitration “(i)n the event any . . . difference of opinion or dispute occurs, whether they concern the interpretation of the . . . Agreement or otherwise The Ironworkers’ arbitration agreement provides “(t)he Board of Arbitration shall have jurisdiction over all questions involving the interpretation and application of any section of this Agreement.”
  The District Court, in its opinion, detailed the unions’ allegations concerning the creation of the sham corporation and examined the evidence on the merits of the claim. The court concluded “this court can go no further than to determine whether or not plaintiffs have made out a prima facie case based on the alter ego or single employer theory.” It refused to send the matter to arbitration because “the evidence and testimony indicate a lack of sufficient common factors to illustrate a single employer or alter ego theory.”
  Any inquiry into the applicable law in this area must begin with the Steelworkers’ Trilogy. United Steelworkers v. American Mfg. Co., 363 U.S. 564, 80 S.Ct. 1343, 4 L.Ed.2d 1403 (1960); United Steelworkers v. Warrior & Gulf Navigation Co., 363 U.S. 574, 80 S.Ct. 1347, 4 L.Ed.2d 1409 (1960); United Steelworkers v. Enterprise Wheel & Car Corp., 363 U.S. 593, 80 S.Ct. 1358, 4 L.Ed.2d 1424 (1960). The teaching of the Trilogy is that arbitration is preferred in the field of labor disputes. “An order to arbitrate . . . should not be denied unless it may be said with positive assurance that the arbitration clause is not susceptible of an interpretation that covers the asserted dispute. Doubts should be resolved in favor of coverage.” Warrior & Gulf, supra, 363 U.S. at 582-583, 80 S.Ct. at 1353. Cf. International Union of Operating Engineers, Local 150, AFL-CIO v. Flair Builders, Inc., 406 U.S. 487, 92 S.Ct. 1710, 32 L.Ed.2d 248 (1972). The role of the court in these cases “is confined to ascertaining whether the party seeking arbitration is making a claim which on its face is governed by the contract.” American Mfg., supra, 363 U.S. at 568, 80 S.Ct. at 1346 (emphasis added). See Amalgamated Clothing Workers of America, AFL-CIO v. Ironall Factories Co., Inc., 386 F.2d 586, 591 (6th Cir. 1967). The Fifth Circuit has termed the standard to be applied the “arguably arbitrable” test. International Union of Operating Engineers Local 279 v. Sid Richardson Carbon Co., 471 F.2d 1175 (5th Cir. 1973); Jacksonville Newspaper Printing Pressmen & Assistants’ Union No. 57 v. Florida Publishing Co., 468 F.2d 824 (5th Cir. 1972), cert. denied, 411 U.S. 906, 93 S.Ct. 1531, 36 L.Ed.2d 196 (1973).
  We hold that the District Court misconstrued its mandate. The duty of the courts is not to determine whether a prima facie case on the merits has been put forth by the party seeking arbitration. It is not the province of the court to look into the facts of the case. Chambers v. Beaunit Corp., 404 F.2d 128, 130 (6th Cir. 1968); American Radiator & Standard Sanitary Corp. v. Local 7, International Brotherhood of Operative Potters, 358 F.2d 455, 458 (6th Cir. 1966). The arbitrator is not to be viewed as a special master who will be called in after a prima facie case on the merits has been made out.
  In the context of this ease, the burden of the unions was not to present a prima facie case on the creation of a sham or alter ego corporation by the employer. The burden was to show that, assuming there was a sham or alter ego corporation created by the Heminger Corp., there would then be a violation of the collective bargaining agreements. We have no doubt that such an asserted violation would be within the scope of the three arbitration agreements in question. In signing these arbitration agreements, the parties agreed to “submit all grievances to arbitration, not merely those that a court may deem to be meritorious.” American Mfg., supra, 363 U.S. at 567, 80 S.Ct. at 1346.
  Heminger has promised to arbitrate grievances concerning the application and interpretation of the collective bargaining agreement. This employer must be held to its promise.
  We find inapposite two N.L.R.B. decisions relied on heavily by Heminger: Carpenters District Council of Houston & Vicinity et al. and Baxter Construction Co., Inc., 201 N.L.R.B. No. 16 (1973); and Gerace Construction, Inc. et al. v. United Brotherhood of Carpenters and Joiners of America, AFL-CIO, Local No. 1654 et al., 193 N.L.R.B. No. 91 (1971). Both of these unfair labor practice proceedings were concerned with the presence or absence of a single employer. There was no issue of arbi-trability in either of those cases. We emphasize that this court is not faced with the question of whether there was a single employer. We simply decide the arbitrability of that claim.
  Reversed and remanded with directions to the District Court to order arbitration between the unions and Boyd G. Heminger, Inc.
instruction: What follows is an opinion from a United States Court of Appeals.
  Intervenors who participated as parties at the courts of appeals should be counted as either appellants or respondents when it can be determined whose position they supported. For example, if there were two plaintiffs who lost in district court, appealed, and were joined by four intervenors who also asked the court of appeals to reverse the district court, the number of appellants should be coded as six.
  When coding the detailed nature of participants, use your personal knowledge about the participants, if you are completely confident of the accuracy of your knowledge, even if the specific information is not in the opinion. For example, if "IBM" is listed as the appellant it could be classified as "clearly national or international in scope" even if the opinion did not indicate the scope of the business. 
  
  Your task concerns the first listed appellant. The nature of this litigant falls into the category "private organization or association", specifically "business, trade, professional, or union (BTPU)". Your task is to determine what subcategory of private association best describes this litigant.