Mr. Justice Douglas
delivered the opinion of the Court.
The information charged that appellee shipped sulfuric acid and hydrofluosilicic acid in interstate commerce and “did knowingly fail to show on the shipping papers the required classification of said property, to wit, Corrosive Liquid, in violation of 49 C. P. R. 173.427.”
Title 18 U. S. C. § 834 (a) gives the Interstate Commerce Commission power to “formulate regulations for the safe transportation” of “corrosive liquids” and 18 U. S. C. § 834 (f) states that whoever “knowingly violates any such regulation” shall be fined or imprisoned.
Pursuant to the power granted by § 834 (a) the regulatory agency promulgated the regulation already cited which reads in part:
“Each shipper offering for transportation any hazardous material subject to the regulations in this chapter, shall describe that article on the shipping paper by the shipping name prescribed in § 172.5 of this chapter and by the classification prescribed in § 172.4 of this chapter, and may add a further description not inconsistent therewith. Abbreviations must not be used.” 49 CFR § 173.427.
The District Court, relying primarily on Boyce Motor Lines, Inc. v. United States, 342 U. S, 337, ruled that the information did not charge a “knowing violation” of the regulation and accordingly dismissed the information.
The United States filed a notice of appeal to the Court of Appeals, 18 U. S. C. § 3731, and in reliance on that section later moved to certify the case to this Court which the Court of Appeals did; and we noted probable jurisdiction, 400 U. S. 990.
Here as in United States v. Freed, 401 U. S. 601, which dealt with the possession of hand grenades, strict or absolute liability is not imposed; knowledge of the shipment of the dangerous materials is required. The sole and narrow question is whether “knowledge” of the regulation is also required. It is in that narrow zone that the issue of “mens rea” is raised; and appellee bears down hard on the provision in 18 U. S. C. § 834 (f) that whoever “knowingly violates any such regulation” shall be fined, etc.
Boyce Motor Lines, Inc. v. United States, supra, on which the District Court relied, is not dispositive of the issue. It involved a regulation governing transporting explosives, inflammable liquids, and the like and required drivers to “avoid, so far as practicable, and, where feasible, by prearrangement of routes, driving into or through congested thoroughfares, places where crowds are assembled, street car tracks, tunnels, viaducts, and dangerous crossings.” The statute punished whoever “knowingly” violated the regulation. Id., at 339. The issue of “mens rea” was not raised below, the sole question turning on whether the standard of guilt was unconstitutionally vague. Id., at 340. In holding the statute was not void for vagueness we said:
“The statute punishes only those who knowingly violate the Regulation. This requirement of the presence of culpable intent as a necessary element of the offense does much to destroy any force in the argument that application of the Regulation would be so unfair that it must be held invalid. That is evident from a consideration of the effect of the requirement in this case. To sustain a conviction, the Government not only must prove that petitioner could have taken another route which was both commercially practicable and appreciably safer (in its avoidance of crowded thoroughfares, etc.) than the one it did follow. It must also be shown that petitioner knew that there was such a practicable, safer route and yet deliberately took the more dangerous route through the tunnel, or that petitioner willfully neglected to exercise its duty under the Regulation to inquire into the availability of such an alternative route.
“In an effort to give point to its argument, petitioner asserts that there was no practicable route its trucks might have followed which did not pass through places they were required to avoid. If it is true that in the congestion surrounding the lower Hudson there was no practicable way of crossing the River which would have avoided such points of danger to a substantially greater extent than the route taken, then petitioner has not violated the Regulation. But that is plainly a matter for proof at the trial. We are not so conversant with all the routes in that area that we may, with no facts in the record before us, assume the allegations of the indictment to be false. We will not thus distort the judicial notice concept to strike down a regulation adopted only after much consultation with those affected and penalizing only those who knowingly violate its prohibition.” Id., at 342-343.
The “mens rea” that emerged in the foregoing discussion was not knowledge of the regulation but knowledge of the safer routes and those that were less safe within the meaning of the regulation. Mr. Justice Jackson, writing in dissent for himself, Mr. Justice Black, and Mr. Justice Frankfurter, correctly said:
“I do not suppose the Court intends to suggest that if petitioner knew nothing of the existence of such a regulation its ignorance would constitute a defense.” 342 U. S., at 345.
There is no issue in the present case of the propriety of the delegation of the power to establish regulations and of the validity of the regulation at issue. We therefore see no reason why the word “regulations” should not be construed as a shorthand designation for specific acts or omissions which violate the Act. The Act, so viewed, does not signal an exception to the rule that ignorance of the law is no excuse and is wholly consistent with the legislative history.
The failure to change the language in § 834 in 1960 should not lead to a contrary conclusion. The Senate approved an amendment deleting “knowingly” and substituting therefor the language “being aware that the Interstate Commerce Commission has formulated regulations for the safe transportation of explosives and other dangerous articles.” But the House refused to agree. As the House Committee stated, its version would “retain the present law by providing that a person must ‘knowingly’ violate the regulations.”
The House Committee noted there was a “judicial pronouncement as to the standards of conduct that make a violation a ‘knowing’ violation.” In St. Johnsbury Trucking Co. v. United States, 220 F. 2d 393, 397, Chief Judge Magruder had concluded that knowledge of the regulations was necessary. But whether the House Committee was referring to Boyce Motor Lines or the opinion of Chief Judge Magruder is not clear since both views of the section were before Congress. It is clear that strict liability was not intended. The Senate Committee felt it would be too stringent and thus rejected the position of the Interstate Commerce Commission. But despite protestations of avoiding strict liability the Senate version was very likely to result in strict liability because knowledge of the facts would have been unnecessary and anyone involved in the business of shipping dangerous materials would very likely know of the regulations involved. Thus in rejecting the Senate version the House was rejecting strict liability. But it is too much to conclude that in rejecting strict liability the House was also carving out an exception to the general rule that ignorance of the law is no excuse.
The principle that ignorance of the law is no defense applies whether the law be a statute or a duly promulgated and published regulation. In the context of these proposed 1960 amendments we decline to attribute to Congress the inaccurate view that that Act requires proof of knowledge of the law, as well as the facts, and that it intended to endorse that interpretation by retaining the word “knowingly.” We conclude that the meager legislative history of the 1960 amendments makes unwarranted the conclusion that Congress abandoned the' general rule and required knowledge of both the facts and the pertinent law before a criminal conviction could be sustained under this Act.
So far as possession, say, of sulfuric acid is concerned the requirement of “mens rea” has been made a requirement of the Act as evidenced by the use of the word “knowingly.” A person thinking in good faith that he was shipping distilled water when in fact he was shipping some dangerous acid would not be covered. As stated in Morissette v. United States, 342 U. S. 246, 250:
“The contention that an injury can amount to a crime only when inflicted by intention is no provincial or transient notion. It is as universal and persistent in mature systems of law as belief in freedom of the human will and a consequent ability and duty of the normal individual to choose between good and evil.”
There is leeway for the exercise of congressional discretion in applying the reach of “mens rea.” United States v. Balint, 258 U. S. 250. United States v. Murdock, 290 U. S. 389, closely confined the word “willfully” in the income tax law to include a purpose to bring about the forbidden result:
“He whose conduct is defined as criminal is one who ‘willfully’ fails to pay the tax, to make a return, to keep the required records, or to supply the needed information. Congress did not intend that a person, by reason of a bona fide misunderstanding as to his liability for the tax, as to his duty to make a return, or as to the adequacy of the records he maintained, should become a criminal by his mere failure to measure up to the prescribed standard of conduct. And the requirement that the omission in these instances, must be willful, to be criminal, is persuasive that the same element is essential to the offense of failing to supply information.” Id., at 396.
In Balint the Court was dealing with drugs, in Freed with hand grenades, in this case with sulfuric and other dangerous acids. Pencils, dental floss, paper clips may also be regulated. But they may be the type of products which might raise substantial due process questions if Congress did not require, as in Murdock, “mens rea” as to each ingredient of the offense. But where, as here and as in Balint and Freedl, dangerous or deleterious devices or products or obnoxious waste materials are involved, the probability of regulation is so great that anyone who is aware that he is in possession of them or dealing with them must be presumed to be aware of the regulation.
Reversed.
The regulatory authority originally granted the Interstate Commerce Commission was transferred to the Department of Transportation by 80 Stat. 939, 49 U. S. C. § 1655 (e) (1964 ed., Supp. V).
See H. R. Rep. No. 1975, 86th Cong., 2d Sess., 10-11.
Id., at 2.
Ibid.
See the HEW Staff Memorandum, id., at 16-19.
S. Rep. No. 901, 86th Cong., 1st Sess., 3.
The Senate language might “well create an almost absolute liability for violation.” H. R. Rep. No. 1975, supra, at 2.