concurring in the judgment of reversal.
I agree that the amendments to the National Firearms Act, 26 U. S. C. §§ 5841-5872 (1964 ed., Supp. V), do not violate the Fifth Amendment's privilege against self-incrimination, and join Part I of the opinion of the Court. However, I do not join Part II of the opinion; although I reach the same result as the Court on the intent the Government must prove to convict, I do so by another route.
I join Part I on my understanding of the Act’s new immunity provision. 26 U. S. C. § 5848 (1964 ed., Supp. Y). The amended registration provisions of the National Firearms Act do not pose any realistic possibility of self-incrimination of the transferee under federal law. An effective registration of a covered firearm will render the transferee's possession of that firearm legal under federal law. It is only appellees’ contention that registration or application for registration will incriminate them under California law that raises the Fifth Amendment issue in this case. Specifically, appellees assert that California law outlaws possession of hand grenades and that registration under federal law would, therefore, incriminate them under state law. Assuming that appellees correctly interpret California law, I think that the Act’s immunity provision suffices to supplant the *611constitutional protection. Section 5848 provides in pertinent part:
“No information or evidence obtained from an application . . . shall ... be used, directly or indirectly, as evidence against that person in a criminal proceeding with respect to a violation of law occurring prior to or concurrently with the filing of the application . . . .”
In my judgment, this provision would prevent a State from making any use of a federal registration or application, or any fruits thereof, in connection with a prosecution under the State’s possession law.1 This would be true even if the State charged a transferee with possession of the firearm on a date after the date the application was filed, because possession is a continuing violation.2 Therefore, for purposes of the State’s possession law, a transferee’s continued possession of a registered firearm would constitute “a violation of law occurring . . . concurrently with the filing of the application.”
I agree with the Court that the Self-Incrimination Clause of the Fifth Amendment does not require that immunity be given as to the use of such information in connection with crimes that the transferee might possibly commit in the future with the registered firearm. The only disclosure required under the amended Act is that the transferee has received a firearm and is in possession of it. Thus, in connection with the present general registration scheme, “[t]he relevant class of activities ‘perme*612ated with criminal statutes,’ ” Mackey v. United States, post, at 710 (Brennan, J., concurring in judgment), is limited to the class of activities relating to possession of firearms. Id., at 707-711. Since I read the statute’s immunity provision to provide immunity co-extensive with the privilege in that regard, I find no Fifth Amendment bar to the enforcement of the federal statute.
The Court’s discussion of the intent the Government must prove to convict appellees of violation of 26 U. S. C. § 5861 (d) (1964 ed., Supp. V) does not dispel the confusion surrounding a difficult, but vitally important, area of the law. This case does not raise questions of “consciousness of wrongdoing” or “blameworthiness.” If the ancient maxim that “ignorance of the law is no excuse” has any residual validity, it indicates that the ordinary intent requirement — mens rea — of the criminal law does not require knowledge that an act is illegal, wrong, or blameworthy. Nor is it possible to decide this case by a simple process of classifying the statute involved as a “regulatory” or a “public welfare” measure. To convict appellees of possession of unregistered hand grenades, the Government must prove three material elements: (1) that appellees possessed certain items; (2) that the items possessed were hand grenades; and (3) that the hand grenades were not registered. The Government and the Court agree that the prosecutor must prove knowing possession of the items and also knowledge that the items possessed were hand grenades. Thus, while the Court does hold that no intent at all need be proved in regard to one element of the offense — the unregistered status of the grenades — knowledge must still be proved as to the other two elements. Consequently, the National Firearms Act does not create a crime of strict liability as to all its elements. It is no help in deciding what level of intent must be proved as *613to the third element to declare that the offense falls within the “regulatory” category.
Following the analysis of the Model Penal Code,3 I think we must recognize, first, that “[t]he existence of a mens rea is the rule of, rather than the exception to, the principles of Anglo-American criminal jurisprudence.” Dennis v. United States, 341 U. S. 494, 500 (1951) (Vinson, C. J., announcing judgment); Smith v. California, 361 U. S. 147, 150 (1959);4 second, that mens rea is not a unitary concept, but may vary as to each element of a crime; and third, that Anglo-American law has developed several identifiable and analytically distinct levels of intent, e. g., negligence, recklessness, knowledge, and purpose.5 To determine the mental element required for conviction, each material element of the offense must be examined and the determination made what *614level of intent Congress intended the Government to prove, taking into account constitutional considerations, see Screws v. United States, 325 U. S. 91 (1945), as well as the common-law background, if any, of the crime involved. See Morissette v. United States, 342 U. S. 246 (1952).
Although the legislative history of the amendments to the National Firearms Act is silent on the level of intent to be proved in connection with each element of the offense, we are not without some guideposts. I begin with the proposition stated in Morissette v. United States, 342 U. S., at 250, that the requirement of mens rea “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.” In regard to the first two elements of the offense, (1) possession of items that (2) are hand grenades, the general rule in favor of some intent requirement finds confirmation in the case law under the provisions replaced by the present amendments. The cases held that a conviction of an individual of illegal possession of unregistered firearms had to be supported by proof that his possession was “willing and conscious” and that he knew the items possessed were firearms. E. g., Sipes v. United States, 321 F. 2d 174, 179 (CA8 1963); United States v. Decker, 292 F. 2d 89 (CA6 1961). Congress did not disapprove these cases, and we may therefore properly infer that Congress meant that the Government must prove knowledge with regard to the first two elements of the offense under the amended statute.
The third element — the unregistered status of the grenades — presents more difficulty. Proof of intent with regard to this element would require the Government to show that the appellees knew that the grenades were *615unregistered or negligently or recklessly failed to ascertain whether the weapons were registered. It is true that such a requirement would involve knowledge of law, but it does not involve “consciousness of wrongdoing” in the sense of knowledge that one’s actions were prohibited or illegal.6 Rather, the definition of the crime, as written by Congress, requires proof of circumstances that involve a legal element, namely whether the grenades were registered in accordance with federal law. The knowledge involved is solely knowledge of the circumstances that the law has defined as material to the offense. The Model Penal Code illustrates the distinction:
“It should be noted that the general principle that ignorance or mistake of law is no excuse is usually greatly overstated; it has no application when the circumstances made material by the definition of the offense include a legal element. So, for example, it is immaterial in theft, when claim of right is adduced in defense, that the claim involves a legal judgment as to the right of property. It is a defense because knowledge that the property belongs to someone else is a material element of the crime and such knowledge may involve matter of law as well as fact. . . . The law involved is not the law defining the offense; it is some other legal rule that characterizes the attendant circumstances that *616are material to the offense.” Model Penal Code § 2.02, Comment 131 (Tent. Draft No. 4, 1955).
Therefore, as with the first two elements, the question is solely one of congressional intent. And while the question is not an easy one, two factors persuade me that proof of mens rea as to the unregistered status of the grenades is not required. First, as the Court notes, the case law under the provisions replaced by the current law dispensed with proof of intent in connection with this element. Sipes v. United States, supra. Second, the firearms covered by the Act are major weapons such as machineguns and sawed-off shotguns; deceptive weapons such as flashlight guns and fountain pen guns; and major destructive devices such as bombs, grenades, mines, rockets, and large caliber weapons including mortars, antitank guns, and bazookas. Without exception, the likelihood of governmental regulation of the distribution of such weapons is so great that anyone must be presumed to be aware of it. In the context of a taxing and registration scheme, I therefore think it reasonable to conclude that Congress dispensed with the requirement of intent in regard to the unregistered status of the weapon, as necessary to effective administration of the statute.
No question of transactional immunity is raised here since the ease involves incrimination under the laws of a jurisdiction different from the one compelling the incriminating information. Piccirillo v. New York, 400 U. S. 548, 552 (Brennan, J., dissenting).
The result would be the same if a transferee moved from a State where possession was legal to a State where possession was illegal. The time when the possession became illegal cannot affect the continuing nature of the act of possession.
ALI Model Penal Code § 2.02, Comment 123-132 (Tent. Draft No. 4, 1955).
“Still, it is doubtless competent for the [government] to create strict criminal liabilities by defining criminal offenses without any element of scienter — though . . . there is precedent in this Court that this power is not without limitations. See Lambert v. California, 355 U. S. 225.” Smith v. California, 361 U. S. 147, 150 (1959). The situations in which strict liability may be imposed were stated by Judge, now Mr. Justice, BlacKMUN: “[W]here a federal criminal statute omits mention of intent and where it seems to involve what is basically a matter of policy, where the standard imposed is, under the circumstances, reasonable and adherence thereto properly expected of a person, where the penalty is relatively small, where conviction does not gravely besmirch, where the statutory crime is not one taken over from the common law, and where congressional purpose is supporting, the statute can be construed as one not requiring criminal intent.” Holdridge v. United States, 282 F. 2d 302, 310 (CA8 1960).
These different levels of intent are defined in the code. ALI Model Penal Code § 2.02 (Prop. Official Draft 1962). This Court has relied on the code’s definitions. Leary v. United States, 395 U. S. 6, 46 n. 93 (1969); Turner v. United States, 396 U. S. 398, 416 n. 29 (1970).
Proof of some crimes may include a requirement of proof of actual knowledge that the act was prohibited by law, or proof of a purpose to bring about the forbidden result. See James v. United States, 366 U. S. 213 (1961); Boyce Motor Lines v. United States, 342 U. S. 337 (1952). United States v. Murdock, 290 U. S. 389 (1933). See generally Note, Counseling Draft Resistance: The Case for a Good Faith Belief Defense, 78 Yale L. J. 1008, 1022-1037 (1969). Cf. Model Penal Code §2.02 (2) (a) (Prop. Official Draft 1962) (definition of “purposely”).