opinion: Per Curiam.
  In 1953, the Alabama Legislature enacted a statute (Ala. Laws 1953, No. 720) which provides that any public employee who joins or participates in a “labor union or labor organization” forfeits the “rights, benefits, or privileges which he enjoys as a result of his public employment.” Section 1 defines a “labor union or labor organization” to include an organization of employees whose purpose is to deal with employers concerning grievances, labor disputes, or conditions of employment. Teachers, certain employees of the State Docks Board and city and county employees, however, are exempted from the provisions of the Act.
  Appellants are an organization composed of employees of governmental and civic agencies, and a member of the organization who is employed by a retail liquor store operated by the Alabama Alcoholic Beverage Control Board. They commenced this action in the United States District Court for the Northern District of Alabama to enjoin the enforcement of the state statute on the grounds that it abridged the freedoms of expression and association of public employees, and that the statute violated the Due Process, Privileges and Immunities, and Equal Protection Clauses of the Fourteenth Amendment.
  The three-judge District Court, convened pursuant to 28 U. S. C. §§ 2281, 2284, withheld the exercise of its jurisdiction, retaining the cause “for a reasonable time to permit the exhaustion of such State administrative and judicial remedies as may be available.” 116 F. Supp. 354, 359. We affirmed that judgment of the District Court. 347 U. S.901.
  Appellant union commenced an action in the Alabama courts to obtain an “authoritative construction” of the state statute. A bill in equity was filed in the Circuit Court of Montgomery County, Alabama, praying that the enforcement of the statute against the union or its members be enjoined, and for a declaratory judgment that the union was not a “labor union or labor organization” within the meaning of the statute. In its complaint, the union denied that the statute applied to it or its members. None of the constitutional contentions presented in the action pending in the United States District Court were advanced in the state court action. After hearing testimony, the Circuit Court of Montgomery County denied the union’s prayer for relief, holding that the statute applied to the union, its members and its activities. The Alabama Supreme Court affirmed. 262 Ala. 285, 78 So. 2d 646. It held that a local union operating under the appellant’s rules and constitution would be subject to the provisions of the Act.
  The case was resubmitted to the three-judge District Court for final decree. The District Court dismissed the action with prejudice, saying that the Alabama courts have not construed the Act “in such a manner as to render it unconstitutional, and, of course, we cannot assume that the State courts will ever so construe said statute.” 146 F. Supp. 214, 216. We noted probable jurisdiction. 352 U. S. 905.
  We do not reach the constitutional issues. In an action brought to restrain the enforcement of a state statute on constitutional grounds, the federal court should retain jurisdiction until a definitive determination of local law questions is obtained from the local courts. One policy served by that practice is that of not passing on constitutional questions in situations where an authoritative interpretation of state law may avoid the constitutional issues. Spector Motor Co. v. McLaughlin, 323 U. S. 101, 105. Another policy served by that practice is the avoidance of the adjudication of abstract, hypothetical issues. Federal courts will not pass upon constitutional contentions presented in an abstract rather than in a concrete form. Rescue Army v. Municipal Court, 331 U. S. 549, 575, 584. The bare adjudication by the Alabama Supreme Court that the union is subject to this Act does not suffice, since that court was not asked to interpret the statute in light of the constitutional objections presented to the District Court. If appellants’ freedom-of-expression and equal-protection arguments had been presented to the state court, it might have construed the statute in a different manner. Accordingly, the judgment of the District Court is vacated, and this cause is remanded to it with directions to retain jurisdiction until efforts to obtain an appropriate adjudication in the state courts have been exhausted.
  It is so ordered.
  Mr. Justice Black took no part in the consideration or decision of this case.
instruction: What follows is an opinion from the Supreme Court of the United States. Your task is to determine the issue area of the Court's decision. Determine the issue area on the basis of the Court's own statements as to what the case is about. Focus on the subject matter of the controversy rather than its legal basis. In specifying the issue in a legacy case, choose the one that best accords with what today's Court would consider it to be. Choose among the following issue areas: "Criminal Procedure" encompasses the rights of persons accused of crime, except for the due process rights of prisoners. "Civil rights" includes non-First Amendment freedom cases which pertain to classifications based on race (including American Indians), age, indigency, voting, residency, military or handicapped status, gender, and alienage. "First Amendment encompasses the scope of this constitutional provision, but do note that it need not involve the interpretation and application of a provision of the First Amendment. For example, if the case only construe a precedent, or the reviewability of a claim based on the First Amendment, or the scope of an administrative rule or regulation that impacts the exercise of First Amendment freedoms. "Due process" is limited to non-criminal guarantees. "Privacy" concerns libel, comity, abortion, contraceptives, right to die, and Freedom of Information Act and related federal or state statutes or regulations. "Attorneys" includes attorneys' compensation and licenses, along with trhose of governmental officials and employees. "Unions" encompass those issues involving labor union activity. "Economic activity" is largely commercial and business related; it includes tort actions and employee actions vis-a-vis employers. "Judicial power" concerns the exercise of the judiciary's own power. "Federalism" pertains to conflicts and other relationships between the federal government and the states, except for those between the federal and state courts. "Federal taxation" concerns the Internal Revenue Code and related statutes. "Private law" relates to disputes between private persons involving real and personal property, contracts, evidence, civil procedure, torts, wills and trusts, and commercial transactions. Prior to the passage of the Judges' Bill of 1925 much of the Court's cases concerned such issues. Use "Miscellaneous" for legislative veto and executive authority vis-a-vis congress or the states.
choices: Criminal Procedure Civil Rights First Amendment Due Process Privacy Attorneys Unions Economic Activity Judicial Power Federalism Interstate Relations Federal Taxation Miscellaneous Private Action