In Sinclair Refining Co. v. Atkinson (1962) 370 U.S. 195, 228, the United States Supreme Court stated: "A District Court entertaining an action under 301 may not grant injunctive relief against concerted activity unless and until it decides that the case is one in which an injunction would be appropriate despite the Norris-LaGuardia Act. When a strike is sought to be enjoined because it is over a grievance which both parties are contractually bound to arbitrate, the District Court may issue no injunctive order until it first holds that the contract does have that effect; and the employer should be ordered to arbitrate, as a condition of his obtaining an injunction against the strike. Beyond this, the District Court must, of course, consider whether issuance of an injunction would be warranted under ordinary principles of equity -- whether breaches are occurring and will continue, or have been threatened and will be committed; whether they have caused or will cause irreparable injury to the employer; and whether the employer will suffer more from the denial of an injunction than will the union from its issuance."