delivered the opinion of the Court.
The issues in this case revolve around the power of a federal District Court to assess damages allegedly caused by a temporary injunction issued by the court but later dissolved on final hearing. These issues grow out of this situation: Respondents in this Court, seventy-six
*623
individuals, partnerships, and corporations operating trucks as common carriers in interstate commerce, filed a bill in the federal District Court to enjoin petitioners here, Missouri officials and agencies, from enforcing against them certain allegedly unconstitutional tax and license features of the Missouri Bus and Truck Law.
1
A single district judge granted a temporary restraining order under which respondents were required to post injunction bonds and under which the contested fees were to be deposited with a trustee during the litigation. But because the bill sought to restrain state officials from enforcing an allegedly unconstitutional state statute, the case was set down for hearing before a three judge District Court pursuant to § 266 of the Judicial Code as amended, 28 U. S. C. § 380. Petitioners, in their answer to respondents’ complaint, counterclaimed for fees and licenses the respondents had failed to pay in the past
2
and later amended the counterclaim to include amounts the respondents failed to deposit with the trustee during the litigation. Ultimately, the three judge court found the Bus and Truck Law constitutional, dissolved the restraining order, dismissed the truck operators’ bill, and also ordered the counterclaim dismissed without prejudice because of “serious doubt as to the right of the de
*624
fendants to maintain” such an action. The truck operators did not' appeal from the dismissal of their bill. Petitioners’ attempt to bring the dismissal of their counterclaim here by direct appeal was dismissed for want of jurisdiction.
1. Should the two additional judges, called to assist the district judge pursuant to § 266, have participated in consideration of the motion to assess damages?
2. Was the District Court correct in holding that its prior denial of the counterclaim was a final adjudication *625 of the issues presented by petitioners’ motion to assess damages?
3. Were the enjoined Missouri officials and agencies, to whom the injunction bonds ran, proper parties to invoke the court’s action for assessment of damages?
4. Did the District Court erroneously exercise its discretionary power, by its refusal to hear and determine the merits of petitioners’ motion to assess damages?
First. We are of opinion that the two judges called in under § 266 to assist the district judge in passing upon the application for injunction should not have participated in consideration of the motion to assess damages. The limited statutory duties of the specially constituted three judge District Court had been fully performed before the motion for assessment of damages was filed. For § 266 of the Judicial Code provides for a hearing by three judges, instead of one district judge, only in connection with adjudication of a very narrow type of controversy — applications for temporary and permanent injunctions restraining state officials from enforcing state laws or orders made pursuant thereto upon the ground that the state statutes are repugnant to the Federal Constitution.* * 4 The motion for damages raised questions not within the statutory purpose for which the two additional judges had been called. Those questions were therefore for the consideration of the District Court in the exercise of its ordinary jurisdiction, and the three judge requirement of § 266 had no application. 5
*626 But the fact that it was mistakenly assumed that the motion should be passed upon by the district judge in association with the two judges previously called did not of itself invalidate the District Court’s judgment dismissing the motion. Though that judgment of dismissal was not appealable directly to this court under § 266, even though participated in by three judges, 6 it was reviewable by the Circuit Court of Appeals, and since it has been so reviewed, the issues presented are properly before us.
Second. The ground assigned by the District Court for denying the motion to assess damages was that by its previous dismissal of petitioners’ counterclaim it had already ruled upon and finally determined the questions raised by the motion. The original counterclaim, however, was dismissed without a hearing on the merits. No evidence was heard. It was dismissed, as the court said at the time, because of “serious doubt as to the right of the defendants to maintain such counterclaim,” and in the order of dismissal it was specified that the action taken was “without prejudice to the right of the defendants ... to maintain an independent action or suit thereon.” We need not here point out the procedural reasons which might have caused the “serious doubt” which prompted the court to dismiss the counterclaim. For even assuming that the court properly dismissed the counterclaim without a hearing on the merits, it does not follow that its dismissal was a final adjudication of either the procedural or the substantive right of petitioners to invoke the court’s jurisdiction by a motion to assess damages. Some of the damages asserted in the *627 motion — such as the costs of the litigation — were not asserted in the counterclaim, and such damages could not well have been determined until after final adjudication of the issues which caused the three judge court to be invoked. The record shows that action on the counterclaim was deferred pending full hearing on the constitutionality of the Missouri statute under attack. This postponement might well be attributed to a belief on the part of the court that the questions raised by the counterclaim were matters which could be better determined after final determination of the issues presented by the original bill for injunction. The judgment dismissing the motion for assessment of damages cannot be supported upon the ground that the issues raised by it had been adjudicated in the prior dismissal of the counterclaim.
Third.
Respondents also seek to support the court’s judgment upon the ground that the enjoined state officials and agencies are not the proper parties to invoke the court’s action for assessment of damages brought about by the injunction. This claim cannot be sustained. The argument on which it rests is that the State Treasurer, not the Public Service Commission, is given statutory power to collect the fees that are in part the basis of the motion to assess damages. But petitioners insist that the Public Service Commission actually collects the fees under customs and rules of long standing, and urges that statutory authority exists for such action by the Commission. But whoever has the statutory authority to collect fees, it is not denied that the Missouri Attorney General, one of the enjoined and petitioning officials, is given exclusive authority to bring suit in the name of and on behalf of the state.
7
And if
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upon a hearing damages are shown to have been suffered within the terms and conditions of the injunction bonds, the district court sitting in equity has ample power to see that whatever sums are recovered go to the proper state officials. In addition to this, respondents are in a poor position to argue that petitioners are not proper parties, for one of the grounds upon which the respondents claimed an injunction against these particular petitioners was that it was they who were threatening to bring actions against respondents to collect the very fees which are now a part of the present motion for assessment of damages. At the instance of the operators, these state officials'were for a period-of fifteen months deprived of all opportunity to collect any fees except those deposited with the trustees pursuant to the terms of the restraining order. Petitioners’ motion alleges that many operators failed to comply with the conditions imposed by the order, and that the state has been deprived of fees that it would have collected but for the injunction. The respondents did not bring their suit nor press their claim upon the assumption that these officials could not and would not protect the interest of the state. On the contrary, they acted upon a directly opposite premise and executed bonds running to the enjoined officials in which they agreed to pay the damages suffered. It is obvious, and was obvious from the beginning, that the main damages would be suffered by the State of Missouri and not by these' petitioners as individuals. It was to protect the state through its officials that the bonds were required. In making this requirement the court acted in harmony with the governing principle “that it is the duty of a court of equity granting injunctive relief to do so upon conditions that will protect all — including the public — whose interests the injunction may affect.”
Inland Steel Co.
v.
United States,
Fourth.
There yet remains the basis upon which the court below affirmed the District Court’s refusal to assess damages — that the jurisdiction to exercise this power is discretionary, and that refusal to exercise the power was not shown to be erroneous. In considering this question, it is of no importance that dealing with petitioners’ motion for assessment of damages would involve long and complicated hearings on issues inappropriate for decision by a three judge court. For as we have pointed out, the issues were appropriate for decision by the single judge of the district. There can be no question of that judge’s right to deal with issues such as those here presented. Under long settled equity practice, courts of chancery have discretionary power to assess damages sustained by parties who have been injured because of an injunctive restraint ultimately determined to have been improperly granted.
Russell
v.
Farley,
Reversed and remanded.
Notes
Mo. Rev. Stats; (1929) § 5272, as amended by Mo. Laws (1931), p. 311. The Missouri officials were the Attorney General, the Superintendent of the State Highway Patrol, the State Highway Commission, and the Public Service Commission. The ground of attack on the statute was that it violated the Federal Constitution and the federal Motor Carrier Act of 1935, 49 Stat. 543, 49 U. S. C. §§ 301-327 (Supp. 1939).
Respondents denied “each and every allegation, statement and thing” contained in the counterclaim. Later they contended that it was the understanding of the parties that should the counterclaim become material, then this pleading could be withdrawn and “an opportunity to plead fully” to the counterclaim be exercised. Petitioners denied that there was any such understanding.
See
Phillips
v.
United States,
A District Court composed of three judges under § 266 of course has jurisdiction to determine every question involved in the litigation pertaining to the prayer for an injunction, in order that a single lawsuit may afford final and authoritative decision of the controversy between the parties.
Railroad Commission
v.
Pacific Gas &
*626
Electric Co.,
See, e. g.,
Public Service Commission
v.
Columbia Terminals Co.,
Mo. Rev. Stats. (1929) §11276. (Mo. Rev. Stats. (1939) § 12901.)
Cf.
United States
v.
Morgan,
