delivered the opinion of the Court.
Petitioners are officials of Oklahoma State and Oklahoma County concerned with enforcement of Oklahoma’s liquor laws. Respondent is a common carrier by motor vehicle authorized by the Interstate Commerce Commission to transport in interstate commerce various commodities, including wines and liquors. See U. S. C. Title 49, c. 8. In regular course of business the respondent-carrier undertook to transport 225 cases of wines and liquors from East St. Louis, Illinois, through Missouri, into Oklahoma and thence to a consignee at Fort Sill, a military reservation within the boundaries of Oklahoma. While the vehicle carrying the liquors was momentarily stopped at Oklahoma City for the purpose of loading and unloading other freight, the petitioner-officials forcibly seized and took away the liquors.
The carrier filed a complaint in the federal District Court alleging that the seizure constituted an unlawful interference with its authorized interstate transportation, and praying that the Court order the officials to return the liquors so that it might deliver them to the consignee at Fort Sill. The answer to the complaint, in substance, admitted the material facts relative to the shipment and seizure of the liquors but denied the allegation of the complaint that the seizure was unlawful. The answer did not allege that judicial proceedings concerning the seized liquor were pending, or were to be commenced, in an *385Oklahoma state court. After a trial on stipulated facts, the District Court ordered the liquors returned to the carrier and forbade the officials to interfere with completion of the shipment. 48 F. Supp. 594. The Circuit Court of Appeals, one Judge dissenting, affirmed. 137 F. 2d 274.
Questions presented in the petition for review concerning important state and federal relationships with regard to federal enclaves prompted us to grant certiorari. 320 U. S. 731. Argument has revealed, however, that the determinative issues are more narrow: (1) Did transportation of the liquors through Oklahoma violate that State’s law so as to justify their seizure? (2) Should the District Court have denied the carrier equitable relief because of the “unclean hands” doctrine, even though seizure of the liquors by the officials was illegal? This second question rests on the disputed premise that introduction of the liquors into Fort Sill would have violated the laws of the United States.
Petitioners do not claim, nor could they claim, that either of these two separate questions should be decided in their favor on the ground that Oklahoma has power to control liquor transactions on the Fort Sill Reservation. With certain minor exceptions not here material, Oklahoma ceded to the United States in 1913 whatever authority it ever could have exercised in the Reservation.1 The Oklahoma Supreme Court has recognized that the general power to govern the Fort Sill area is vested in the United States, not in Oklahoma,2 and our decisions lead to the same conclusion.3
*386First. Since power to govern Fort Sill is in the United States, and since the seized liquors were not to be sold, delivered or otherwise disposed of in Oklahoma proper, as distinguished from Fort Sill, the only Oklahoma laws called to our attention which could have justified the seizure are those which apply to liquor transportation. No Oklahoma law purports on its face to prohibit or regulate interstate shipments of liquor into and through the state to another state, or to an area subject to the exclusive jurisdiction of the United States. And we were informed at the bar by Oklahoma’s legal representative that no state statute had been construed by any state court as applying to such through shipments. Oklahoma law does make it unlawful “to import, bring, transport, or cause to be brought or transported into the State . . . intoxicating liquor . . . without a permit ... as hereinafter provided.” Okla. Stat. (1941) Title 37, § 41. The argument is that the Oklahoma legislature intended this statute to apply to liquor imported into the Fort Sill Reservation because the latter is located within the exterior boundaries of Oklahoma. Were this statute intended to do no more than provide a means whereby the state could protect itself from illegal liquor diversions within the area which Oklahoma has power to govern, the interpretation asked might well be an acceptable one. Duckworth v. Arkansas, 314 U. S. 390; Carter v. Virginia, 321 U. S. 131. But the statute has no such limited purpose. No permit to transport liquor into Oklahoma can be obtained at all except for scientific, mechanical, medicinal, industrial, or sacramental purposes. Okla. Stat. (1941) Title 37, § 42. To construe the state statute in the manner urged would be to say that, although Oklahoma admittedly has no power directly to regulate the liquor traffic on the Reservation, the Oklahoma legislature intended practically to exclude from the Reservation liquor which might be put to legal uses under controlling United States laws. Neither the words nor *387the scheme of the statute in question, nor any other-relevant material pointed out to us, indicate that the Oklahoma legislature had such a purpose. Had the legislature expressed such a purpose, questions would be raised which we need not here consider. See Collins v. Yosemite Park & Curry Co., 304 U. S. 518, 533; Pacific Coast Dairy v. Department of Agriculture, 318 U. S. 285, 295. Consequently, we find no justification for the seizure in Oklahoma law.
Second. But it is said that despite the fact the seizure was illegal and wholly without justification, the consignee could not have received the liquors without violating the laws of the United States and for that reason the District Court should have denied the carrier any relief under the “clean hands” doctrine.
We may assume that because of the clean hands doctrine a federal court should not, in an ordinary case, lend its judicial power to a plaintiff who seeks to invoke that power for the purpose of consummating a transaction in clear violation of law.4 But this does not mean that courts must always permit a defendant wrongdoer to retain the profits of his wrongdoing merely because the plaintiff himself is possibly guilty of transgressing the law in the transactions involved.5 The maxim that he who comes into equity must come with clean hands is not applied by way of punishment for an unclean litigant but “upon considerations that make for the advancement of right and justice.” Keystone Driller Co. v. General Excavator Co., 290 U. S. 240, 245. It is not a rigid formula which “trammels the free and just exercise of discretion.” Ibid., 245, 246. *388Therefore, before deciding the applicability of the maxim to the case at hand, we must examine the particular transactions and circumstances involved together with the federal laws which are alleged to taint these transactions with illegality.
As shown by the stipulated facts in this record, the circumstances of the liquor shipment were as follows: Fort Sill had an Officers’ Club, which provided among other things an officers’ mess, living quarters for some Officers, and other customary club facilities. Several hundred Officer-members gave to the Club Secretary, himself an Officer, separate written orders for liquor together with money or checks in payment for the respective orders. Acting for the Officer-members, the Secretary telephoned from Fort Sill to a dealer at East St. Louis, Illinois, and ordered the liquors shipped to the Club. The dealer delivered the liquors to the respondent-carrier under a uniform through bill of lading. It was this shipment which the state officials seized. Had the shipment not been seized it would have arrived at the Club for delivery to the several Officers who had paid for it.
It is first contended that purchase and delivery of the liquors were in violation of U. S. C. Title 10, § 1350, set out in the margin.6 The agreed facts, summarized above, sufficiently show that the transactions were not in violation of this statute.
Petitioners next argue that the liquor transactions here involved were in violation of the assimilative crimes statute.7 This statute, it is said, adopts all of the various *389penal statutes of Oklahoma relating to liquor and makes them the federal law applicable to the Fort Sill Reservation. Cf. United States v. Press Publishing Co., 219 U. S. 1; Franklin v. United States, 216 U. S. 559. Petitioners’ argument as to the applicability of the assimilative crimes statute raises at least three distinct questions, no one of which is easily resolved: (1) Which, if any, of the Oklahoma penal statutes are so designed that they could be adopted by the assimilative crimes statute and applied to Fort Sill?8 See opinions of Circuit Court of Appeals, supra; cf. Murray v. Gerrick & Co., 291 U. S. 315. (2) If there are Oklahoma statutes which could be so adopted, are *390all or any of them in conflict with federal policies as expressed by Acts of Congress other than the assimilative crimes statute or by valid Army Regulations9 which have the force of law?10 Cf. Stewart & Co. v. Sadrakula, 309 U. S. 94, 99-104. (3) Assuming that certain Oklahoma statutes are adaptable, and are not inconsistent with federal policies, would such statutes make penal the liquor transactions here stipulated to have taken place? Inextricably involved in each of the three questions is the further problem of whether certain of the Oklahoma liquor statutes may be inconsistent with Oklahoma’s constitution as interpreted by the Oklahoma Supreme Court. See opinions of the Circuit Court of Appeals, supra; Ex parte Wilson, 6 Okla. Cr. 451, 119 P. 596; Morse v. State, 63 Okla. Cr. 445, 77 P. 2d 757.
Considering the difficulty and importance of a correct decision of the novel issues which an attempt to construe this federal criminal statute would present, together with the other circumstances of the present ease, we are convinced that in the interest of sound administration of justice we should refrain from a complete exploration of these issues in this proceeding, especially since these is*391sues are only collateral to the principal issue of the legality of the seizure of the liquor. Were we to decide that the assimilative crimes statute is not applicable to this shipment of liquors, we would, in effect, be construing a federal criminal statute against the United States in a proceeding in which the United States has never been represented. And, on the other hand, should we decide the statute outlaws the shipment, such a decision would be equivalent to a holding that more than 200 Army Officers, sworn to support the Constitution, had participated in a conspiracy to violate federal law. Not only that, it would for practical purposes be accepted as an authoritative determination that all army reservations in the State of Oklahoma must conduct their activities in accordance with numerous Oklahoma liquor regulations, some of which, at least, are of doubtful adaptability. And all of this would be decided in a case wherein neither the Army Officers nor the War Department nor the Attorney General of the United States have been represented, and upon a record consisting of stipulations between a private carrier and the legal representatives of Oklahoma.
Nor is it any answer to say that the carrier should be compelled to sue in the Oklahoma state courts to reclaim the liquors in order to give the Oklahoma courts the opportunity collaterally to pass upon the question of whether these liquor transactions violate the federal assimilative crimes statute. That broad question, though some parts of it involve a consideration of the proper scope of the state law adopted by the federal government, is in the final analysis a question of the correct interpretation of a federal criminal statute, and therefore an issue upon which federal courts are not bound by the rulings of state courts. Puerto Rico v. Shell Co., 302 U. S. 253, 266. Indeed Congress has vested in the federal courts exclusive jurisdiction over the trial of all federal crimes. Judicial Code § 256 as amended, 28 U. S. C. § 371. And so, even if the carrier *392could bring suit in an Oklahoma state court to reclaim the liquor, a point which is itself subject to some doubt,11 the federal District Court should not for that reason refuse relief in the present suit.
The ultimate question in this part of the case is whether the carrier, whose complete good faith is in no way questioned, should have the court’s doors shut to it. So to hold would be to say that the state officials, who so far as this record shows, had no search warrant or judicial process of any kind,12 could retain liquors which they seized without authority of law. We do not find here any “unconscientious or inequitable attitude” on the part of the carrier. International News Service v. Associated Press, 248 U. S. 215, 245. And so far as this record shows, the carrier, in seeking relief in the courts against the unlawful seizure, has proceeded in the only “practicable and adequate way”13 available.
If the carrier’s delivery of these liquors on the Fort Sill Reservation would violate any federal law, federal agen*393cies exist which are charged with responsibilities to institute appropriate proceedings against the carrier in federal tribunals. In such proceedings the parties would be the United States and the carrier, and the issue of violation of federal laws would be directly, and not collaterally, presented. The complicated federal questions involved, concerning various federal statutes as well as Army rules and regulations, could be answered upon an adequate presentation of all factors essential to a right and just determination.
And, similarly, if the several hundred Army Officers who ordered and paid for these liquors have acted contrary to United States Statutes, Army Regulations, or Orders of the Post Commandant, it is not to be doubted that the Army or some other United States agency is capable of determining what course shall be pursued. Should the United States determine to proceed in the matter it could do so at such time and place as least would hamper essential military training, and the Army Officers would be heard before they would be stigmatized as law breakers and subjected as such to Army discipline. We will not, at this time, and upon this inadequate record, resolve all doubts against the lawfulness of their conduct in order to deny relief against a plainly unlawful seizure of their property from an interstate carrier whose good faith has not been questioned.
Affirmed.
Oklahoma Laws, 1913, c. 52, p. 90.
See Utley v. State Industrial Commission, 176 Okla. 255, 55 P. 2d 762; In re Annexation of Reno Quartermaster Depot Military Reservation, 180 Okla. 274, 69 P. 2d 659.
See Collins v. Yosemite Park Co., 304 U. S. 518, 533; Pacific Coast Dairy v. Department of Agriculture, 318 U. S. 285, 294.
See generally 2 Pomeroy’s Equity Jurisprudence (5th Ed.) §§ 402, 403. Cf. Bentley v. Tibbals, 223 F. 247, 252; Bonnie & Co. v. Bonnie Bros., 160 Ky. 487, 495, 169 S. W. 871.
See, e. g., Catts v. Phalen, 2 How. 376; Kinsman v. Parkhurst, 18 How. 289, 293; Stark v. Grant, 16 N. Y. S. 526; Martin v. Hodge, 47 Ark. 378, 1 S. W. 694.
“The sale of or dealing in, beer, wine or any intoxicating liquors by any person in any post exchange or canteen or army transport or upon any premises used for military purposes by the United States, is hereby prohibited. The Secretary of War is hereby directed to carry the provisions of this section into full force and effect.” 31 Stat. 758; U. S. C. Title 10, § 1350. See Note 9, infra.
“Whoever, within the territorial limits of any State, . . . but within or upon any of the places now existing or hereafter reserved *389or acquired, described in section 272 of the Criminal Code . . ., shall do or omit the doing of any act or thing which is not made penal by any laws of Congress, but which if committed or omitted within the jurisdiction of the State, Territory, or district in which such place is situated, by the laws thereof in force on February 1, 1940, and remaining in force at the time of the doing or omitting the doing of such act or thing, would be penal, shall be deemed guilty of a like offense and be subject to a like punishment.” 54 Stat. 234, U. S. C. Title 18, § 468. Section 272 of the Criminal Code, referred to in this Act, is broad enough to include the Fort Sill Reservation. 35 Stat. 1143.
The Oklahoma liquor statutes pertaining to liquor imports provide one illustration of the difficulties inherent in this question. These penal statutes are designed to enforce a system of licensing such imports by special permits issued by a state agency. Okla. Stat. (1941) Title 37, §§ 41-48. Importation of liquors without a special permit is made penal. Ibid., §§ 41, 46. To hold, therefore, that the assimilative crimes statute adopts Oklahoma’s penal liquor laws the Court might further have to hold that that statute compels federal officials on the Fort Sill Reservation to apply for and obtain state permits before they can lawfully import any liquors for any purpose. And a strong argument might be made that had Congress intended such a drastic result, it would have considered the problem and used more express language. See Note 7, supra; Senate Report No. 1699, Senate Judiciary Committee, 76th Cong., 3d Sess.; House Report No. 1584, House Judiciary Committee, 76th Cong., 3d Sess. Cf. Collins v. Yosemite Park Co., 304 U. S. 518, 533.
Army regulations have declared certain liquor policies for Army reservations generally. See, e. g., A. G. 250.1 (1-20-43), concerning the sale of liquor upon premises used for military purposes by the United States, published by the War Department on January 25, 1943, in Circular No. 29; and A. R. 210-65, concerning Army Exchanges, published by the War Department on March 19, 1943. Petitioners have not contended that the liquor transactions here were contrary to any Army Regulations, and no Regulations have come to our attention which would indicate that there is a basis for such a contention. Whether the declaration of policies contained in these various regulations indicates an intention of the War Department to permit all liquor transactions not expressly prohibited, and whether, if it does, the War Department has the power under Acts of Congress to permit such transactions, seem open questions.
Standard Oil Co. v. Johnson, 316 U. S. 481, 484.
Nothing in the record or briefs justifies the conclusion that the carrier could bring such a proceeding in the state courts. And see Okla. Stat. (1941) Title 37, §§ 72, 86, and 89; Blunk v. Waugh, 32 Okla. 616, 122 P. 717; Lee v. State, 180 Okla. 643, 71 P. 2d 1090; cf. 1942 Chevrolet Automobile Motor No. BA-193397 v. State, 191 Okla. 26, 27, 128 P. 2d 448. Nor has there been any attempt to show that, if the carrier could bring such a proceeding, the Army Officers, the War Department, and the Attorney General of the United States could intervene on the collateral issue of “clean hands.”
Under Oklahoma law there are no “property rights” in liquor. Okla. Stat. (1941) Title 37, §72. Officers with power to execute criminal process may arrest without a warrant one who violates the state liquor laws, and seize the property used in the violation, and it is their duty to take the property before a Court which may order it forfeited and destroyed. Ibid., §§ 89, 90. As stated in the body of the opinion, the record does not show that proceedings of any kind were ever instituted, or sought to be instituted, in the state courts.
McFarland v. American Sugar Refining Co., 241 U. S. 79, 84-85; see also Bowman v. Chicago & Northwestern Ry. Co., 125 U. S. 465.