Opinion of the Court. 390 U.S. The courts below viewed petitioner's complaint as in effect a plea for a writ of mandamus and relied on a long line of cases which have interpreted the All Writs Act 2 to deny power to issue this writ when it is the only relief sought. A writ of mandamus, so these cases hold, can issue only in aid of jurisdiction acquired to grant some other form of relief. See M'Intire v. Wood, 7 Cranch 504 (1813); Rosenbaum v. Bauer, 120 U. S. 450 (1887); Covington Bridge Co. v. Hager, 203 U. S. 109 (1906). We think, however, that the courts below erred in concluding that the relief sought here is "mandamus" within the meaning of these cases. Practically all the cases relied on by respondent and the courts below involved mandamus in its original sense-a suit against a public officer to compel performance of some "ministerial" duty. Although the word "mandamus" is also frequently used to describe orders that compel affirmative action by private parties, the considerations that come into play here certainly differ from the problems involved when the courts seek to compel action by public officials. So far as we are aware, there is only one case in which this Court has held a federal district court without jurisdiction to issue a writ of mandamus against a private party. In Knapp v. Lake Shore R. Co., 197 U. S. 536 (1905), the Interstate Commerce Commission had filed a "petition for mandamus" in the federal court, seeking to compel a railroad company to file certain reports as required by § 20 of the Interstate Commerce Act. The Court applied the principle of the earlier cases involving public officers and held that mandamus would not lie against the railroad company defendant. But the Court was careful to note that relief against the railroad might 21 Stat. 81 (1789), as amended, 28 U. S. C. § 1651 (a): "The Supreme Court and all courts established by Act of Congress may issue all writs necessary or appropriate in aid of their respective jurisdictions and agreeable to the usages and principles of law." 606 Opinion of the Court. be available in the form of a "writ of injunction or other proper process, mandatory or otherwise." Id., at 543. The distinction drawn by the Court in Knapp between mandamus and a mandatory injunction seems formalistic in the present day and age, but it must be remembered that Knapp was decided before the simplification of the rules of pleading and, more importantly, before the merger of law and equity. Since a writ of mandamus could be issued only in an action at law, while an injunction, whether mandatory or prohibitive, was an equitable remedy, the distinction referred to in Knapp was a familiar one in the judicial system of the time. We need not now decide whether Knapp properly extended the mandamus bar to suits for relief against private parties or even whether the distinction between mandamus and mandatory injunctions can survive the merger of law and equity and the simplification of the rules of pleading. In the present case petitioner did not even fall into the trap of using the possibly fatal label, "mandamus"; instead he simply asked the court "to order the defendant to permit plaintiff to examine [its records]." Thus, even under the broadest possible reading of the Knapp decision, the All Writs Act would not deny a federal court power to issue the relief sought here. We find no other principle of federal law, whether judge-made, statutory, or constitutional, which bars the granting of a mandatory remedy here. Petitioner undoubtedly has a right, under the substantive law of the State, to inspect the records of the corporation in which he holds stock, and since he has no adequate remedy at law, the federal court has jurisdiction to grant relief under its traditional equity power. We need not decide whether this is a case where such a federal remedy can be provided even in the absence of a similar state remedy, Skelly Oil Co. v. Phillips Co., 339 U. S. 667, 674 (1950); Opinion of the Court. 390 U.S. cf. Guffey v. Smith, 237 U. S. 101 (1915), because it is clear that state law here also provides for enforcement of the shareholder's right by a compulsory judicial order. See Pa. Stat. Ann., Tit. 12, § 1911 (1967). While the State labels the right of action "mandamus," what the Pennsylvania statute actually does is to authorize an action to compel Pennsylvania corporations to permit inspection of their records by their shareholders, and the label used under state practice of course has no bearing on the question whether the federal courts have power to grant the kind of relief actually sought. Consequently the District Court here does have power to issue the proper orders to enforce petitioner's state-granted right to inspect the corporate records. The judgment of the Court of Appeals is reversed and the cause is remanded to that court for further proceedings consistent with this opinion. It is so ordered. Syllabus. CAMERON ET AL. v. JOHNSON, GOVERNOR OF MISSISSIPPI, ET AL. APPEAL FROM THE UNITED STATES DISTRICT COURT FOR THE SOUTHERN DISTRICT OF MISSISSIPPI. No. 699. Argued March 5-6, 1968.-Decided April 22, 1968. Appellants, to protest racial voting discrimination and encourage Negro registration, picketed the Forrest County, Mississippi, voting registration office in the county courthouse each weekday from January 23 to May 18, 1964, walking in a "march route" set off by the sheriff with barricades to facilitate access to the courthouse. On April 8 the legislature enacted the Mississippi Anti-Picketing Law, which, as amended, prohibits "picketing . . . in such a manner as to obstruct or unreasonably interfere with free ingress or egress to and from any county... courthouses. ..." On April 9 the sheriff read the new law to the pickets, ordered them to disperse, and removed the barricades. When the pickets the next morning resumed marching along the now unmarked route they were arrested for violating the AntiPicketing statute. Other arrests were made that afternoon, on April 11, and on May 18. On April 13 appellants brought this action seeking a judgment declaring that the Anti-Picketing Law is an invalid regulation of expression because of overbreadth and vagueness and an injunction against its enforcement in the prosecutions against them or otherwise, contending that the prosecutions were solely to discourage their freedom of expression. Following initial dismissal of the complaint and this Court's remand (381 U. S. 741) for reconsideration in the light of the intervening decision in Dombrowski v. Pfister, 380 U. S. 479, an evidentiary hearing was held and the three-judge District Court again dismissed the complaint, holding that the statute was not void on its face and that appellants had failed to show sufficient irreparable injury to warrant injunctive relief. Held: 1. The Mississippi Anti-Picketing Law is a valid regulatory statute; it is clear and precise and is not overly broad since it does not prohibit picketing unless it obstructs or unreasonably interferes with ingress and egress to or from the courthouse. Pp. 615-617. Opinion of the Court. 390 U.S. 2. This Court's independent examination of the record does not disclose that the officials acted in bad faith to harass appellants' exercise of the right to free expression; that the statute was adopted to halt appellants' picketing; or that the State had no expectation of securing valid convictions. This is therefore not a case where a federal equity court "by withdrawing the determination of guilt from state courts could rightly afford [appellants] any protection which they could not secure by prompt trial and appeal pursued to this Court." Douglas v. City of Jeannette, 319 U. S. 157, 164. Dombrowski, supra, distinguished. Pp. 617-622. 262 F. Supp. 873, affirmed. Benjamin E. Smith and Arthur Kinoy argued the cause for appellants. With them on the brief were William M. Kunstler, Morton Stavis and Bruce C. Waltzer. Will S. Wells, Assistant Attorney General of Mississippi, argued the cause for appellees. With him on the brief were Joe T. Patterson, Attorney General, and William A. Allain, Assistant Attorney General. MR. JUSTICE BRENNAN delivered the opinion of the Court. Appellants brought this action for declaratory and injunctive relief in the District Court for the Southern District of Mississippi. They sought a judgment declaring that the Mississippi Anti-Picketing Law 1 is an overly 1 1 The statute as amended is codified as Miss. Code Ann. § 2318.5 (Supp. 1966), and in pertinent part provides: "1. It shall be unlawful for any person, singly or in concert with others, to engage in picketing or mass demonstrations in such a manner as to obstruct or unreasonably interfere with free ingress or egress to and from any public premises, State property, county or municipal courthouses, city halls, office buildings, jails, or other public buildings or property owned by the State of Mississippi, or any county or municipal government located therein, or with the transaction of public business or administration of justice therein or thereon conducted or so as to obstruct or unreasonably interfere |