Defendant-Appellant Robert Lee Whaley appeals his conviction under 18 U.S.C. § 2250(a) for failure to register in accordance with the Sex Offender Registration and Notification Act (“SORNA”). We affirm.
I
Whaley stipulated to the relevant facts as part of a plea agreement. In 1999, Whaley was convicted, under Kansas law, of aggravated sexual battery in Marshall County, Kansas, and sentenced to 57 months of imprisonment. Kansas law also required Whaley to register as a sex offender upon his release from prison, and he signed notices explaining his registration obligation in 1999 and 2003. Both notices informed Whaley, inter alia, that if he moved to another state, he was required to register in that state within ten days.
Whaley registered without incident through April 5, 2007. Sometime before June 11, 2007, he moved without leaving a forwarding address and did not update his registration. On March 5, 2008, Whaley was found in Texas, and he admitted to having moved from Kansas to Texas between April 2007 and March 2008 without registering as a sex offender in Texas or updating his registration in Kansas.
On March 12, 2008, Whaley was indicted on one count of violating 18 U.S.C. § 2250(a) by traveling in interstate commerce and knowingly failing to register and update a registration as required under SORNA. Whaley moved to dismiss the indictment on various constitutional grounds, and the district court denied the motion. Whaley then entered a conditional guilty plea, reserving the right to raise his constitutional challenges on appeal. Whaley was sentenced to 21 months’ imprisonment followed by five years of supervised release. He timely filed a notice of appeal.
II
Whaley puts forth several constitutional challenges to his conviction. We review these challenges de novo.
See United States v. Luna,
SORNA was enacted July 27, 2006, more than three years after Whaley was released from prison in Kansas. It requires all sex offenders to “register, and keep the registration current, in each jurisdiction where the offender resides, *257 where the offender is an employee, and where the offender is a student.” 42 U.S.C. § 16913(a). The rules for initial and updated registration are as follows:
(a) In general. A sex offender shall register, and keep the registration current, in each jurisdiction where the offender resides, where the offender is an employee, and where the offender is a student. For initial registration purposes only, a sex offender shall also register in the jurisdiction in which convicted if such jurisdiction is different from the jurisdiction of residence.
(b) Initial registration
The sex offender shall initially register—
(1) before completing a sentence of imprisonment with respect to the offense giving rise to the registration requirement; or
(2) not later than 3 business days after being sentenced for that offense, if the sex offender is not sentenced to a term of imprisonment.
(c) Keeping the registration current
A sex offender shall, not later than 3 business days after each change of name, residence, employment, or student status, appear in person in at least 1 jurisdiction involved pursuant to subsection (a) of this section and inform that jurisdiction of all changes in the information required for that offender in the sex offender registry. That jurisdiction shall immediately provide that information to all other jurisdictions in which the offender is required to register.
(d) Initial registration of sex offenders unable to comply with subsection (b) of this section
The Attorney General shall have the authority to specify the applicability of the requirements of this subchapter to sex offenders convicted before July 27, 2006 or its implementation in a particular jurisdiction, and to prescribe rules for the registration of any such sex offenders and for other categories of sex offenders who are unable to comply with subsection (b) of this section.
42 U.S.C. § 16913. SORNA provides a federal criminal penalty for traveling in interstate commerce and failing to register or update a registration:
(a) In general — Whoever—(1) is required to register under the Sex Offender Registration and Notification Act ... (2)(B) travels in interstate or foreign commerce ...; and (3) knowingly fails to register or update a registration as required by the Sex Offender Registration and Notification Act ... shall be fined under this title or imprisoned not more than 10 years, or both.
18 U.S.C. § 2250(a). SORNA directs the Attorney General to “maintain a national database ... for each sex offender____” 42 U.S.C. § 16919(a). In addition, SOR-NA directs each state “to substantially implement this subchapter” or lose “10 percent of the funds that would otherwise be allocated” to the state under the Omnibus Crime Control and Safe Streets Act of 1968 for a given year. Id. § 16925(a). Among other things, implementation requires the states to: “maintain a jurisdiction-wide sex offender registry conforming to the requirements of [SORNA],” id. § 16912(a); “provide a criminal penalty” for a sex offender’s failure to register, id. § 16913(e); and “immediately ... provide the information in the registry” about an offender who has registered or updated a registration to, among other entities, the Attorney General, local law enforcement agencies, and certain social service and volunteer organizations that work with children, id. § 16921(b).
*258 III
A
We first consider Whaley’s argument that the registration, 42 U.S.C. § 16913, and penalty, 18 U.S.C. § 2250, provisions of SORNA exceed Congress’s authority under the Commerce Clause. The Commerce Clause of the U.S. Constitution gives Congress the power “[t]o regulate commerce with foreign nations, and among the several states, and with the Indian tribes.” U.S. Const, art. I, § 8. The Supreme Court has identified three general categories of activity that Congress may regulate under the Commerce Clause:
First, Congress may regulate the use of the channels of interstate commerce. Second, Congress is empowered to regulate and protect the instrumentalities of interstate commerce, or persons or things in interstate commerce, even though the threat may come only from intrastate activities. Finally, Congress’ commerce authority includes the power to regulate those activities having a substantial relation to interstate commerce, i.e., those activities that substantially affect interstate commerce.
United States v. Lopez,
Whaley asserts that the penalty provision can only be justified under the third
Lopez
prong as it does not regulate the channels of interstate commerce nor concern the regulation of persons or things in interstate commerce. We disagree. Because § 2250 applies only to those failing to register or update a registration after traveling in interstate commerce — in this case, Whaley traveled from Kansas to Texas — it falls squarely under the first
Lopez
prong.
See United States v. Kung-Shou Ho,
*259
Whaley similarly asserts that § 16913 can only be justified under the third
Lopez
prong — and indeed, § 16913 plainly applies to sex offenders not in interstate commerce. In making this argument, however, Whaley treats § 16913 as if it were a stand alone statute. We think that it must instead be analyzed in connection with § 2250. Both provisions were enacted as part of the Adam Walsh Child Protection and Safety Act of 2006, Pub.L. No. 109-248, 120 Stat. 587, and are clearly complementary: without § 2250, § 16913 lacks federal criminal enforcement, and without § 16913, § 2250 has no substance. Section 2250 is plainly aimed at ensuring that sex offenders register and update previous registrations when moving among jurisdictions.
See, e.g., United States v. Dixon,
Moreover, SORNA’s focus on the problem of sex offenders escaping their registration requirements through interstate travel — rather than on requiring sex offender registration generally — is indicated by the fact that although “[b]y the time that SORNA was enacted in 2006, every State and the District of Columbia had enacted a sex offender registration law,”
United States v. Gould,
Thus, considering § 16913 together with § 2250 and SORNA as a whole, § 16913’s registration requirements are a means of furthering the goal of preventing offenders from “slipping through the cracks” by changing jurisdictions.
See Ambert,
As the Court said in the Shreveport Rate Cases, the Necessary and Proper Clause does not give “Congress ... the authority to regulate the internal commerce of a State, as such,” but it does allow Congress “to take all measures necessary or appropriate to” the effective regulation of the interstate market, “although intrastate transactions ... may thereby be controlled.”234 U.S., at 353 ,34 S.Ct. 833 ,58 L.Ed. 1341 ; see also Jones & Laughlin Steel Corp., 301 *261 U.S., at 38,57 S.Ct. 615 ,81 L.Ed. 893 (the logic of the Shreveport Rate Cases is not limited to instrumentalities of commerce).
Raich,
Applying this standard here, we conclude that requiring sex offenders to register both before and after they travel in interstate commerce — which clearly facilitates monitoring those movements and which has a minimal practical impact on intrastate sex offenders (who cannot be punished under federal law for failure to register unless and until they travel in interstate commerce
4
) — is “reasonably adapted” to the goal of ensuring that sex offenders register and update previous registrations when moving among jurisdictions.
See Ambert,
B
Whaley also argues that his conviction violates the Due Process Clause because he never received notice that he was required to register under SORNA. Whaley was notified of his obligation to register as a sex offender under Kansas law, but he was never directly notified of the requirement to register under SORNA or the increased federal penalties for failing to register under SORNA. A provision of SORNA, 42 U.S.C. § 16917, addresses notification of offenders. Because Whaley was released from prison before SORNA was enacted, he was not informed of the federal registration requirement upon release from custody as described in § 16917(a). Section 16917(b) instructs the Attorney General to “prescribe rules for the notification of sex offenders who cannot be registered in accordance with subsection (a) of this section.” At the time of Whaley’s indictment, the Attorney General had not yet issued those rules. 5
*262
In general, ignorance of the law is not a defense to criminal prosecution.
See, e.g., Ratzlaf v. United States,
Whaley relies on
Lambert.
Unlike the defendant in
Lambert;
however, Whaley was aware that he was required to register his address with the government.
Lambert
relied on the passive nature of the crime
combined
with the lack of “circumstances which might move one to inquire as to the necessity of registration.”
Lambert,
C
Finally, Whaley argues that the section of SORNA authorizing the Attor *263 ney General to issue regulations is an impermissible delegation of legislative authority to the executive branch. That section states:
(d) Initial registration of sex offenders unable to comply with subsection (b) of this section
The Attorney General shall have the authority to specify the applicability of the requirements of this subchapter to sex offenders convicted before July 27, 2006 or its implementation in a particular jurisdiction, and to prescribe rules for the registration of any such sex offenders and for other categories of sex offenders who are unable to comply with subsection (b) of this section.
42 U.S.C. § 16913(d). Under Whaley’s reading, this statute gives the Attorney General the authority to determine whether SORNA’s registration requirements apply to persons convicted before July 27, 2006. 7
A circuit split exists as to what § 16913(d) authorizes the Attorney General to do. The Eighth and Tenth Circuits have held that the statute was retroactively applicable from the time of its enactment because § 16913(d) did not authorize the Attorney General to regulate the
applicability
of SORNA to pre-enactment sex offenders, but only to create procedures for
notifying
them of their obligations under the new law.
See Hinckley,
We need not decide that question here, however, because even assuming arguendo that Whaley’s interpretation is correct and that the statute delegates broad authority to the Attorney General to determine the retroactive applicability to SORNA, that delegation would be permissible under the nondelegation doctrine.
The nondelegation doctrine provides that “Congress generally cannot delegate its legislative power to another branch.”
United States v. Mistretta,
The delegation to the Attorney General to determine the retroactive applicability of SORNA is well within the limits of permissible delegation. SORNA’s statement of purpose, to “establish! ] a comprehensive national system” of sex offender registration to “protect the public from sex offenders and offenders against children,” 42 U.S.C. § 16901, is an intelligible principle that guides the Attorney General in exercising his discretion. Moreover, the authority delegated is relatively small.
See Ambert,
IV
For the foregoing reasons, the judgment of the district court is AFFIRMED.
Notes
. Our decision is consistent with the other circuits to have considered the issue.
See
*259
United States v. Gould,
.
See also Gould,
. We recognize the necessity of maintaining the "distinction between what is truly national and what is truly local” so as not to "convert congressional authority under the Commerce Clause to a general police power,”
Lopez,
. Or meet the other jurisdictional requirements of § 2250(a).
. The regulations were issued on July 2, 2008. See The National Guidelines for Sex Offender Registration and Notification ("SORNA Guidelines”), 73 Fed.Reg. 38030, 38063 (July *262 2, 2008). Whaley was indicted on March 12, 2008.
. Whaley also argues that because the government did not inform him of SORNA’s requirements, he could not have “knowingly” failed to register under § 2250(a). Assuming
arguendo
that Whaley preserved this argument in his conditional plea, it is meritless. As noted above, ignorance of the law is not a defense, Whaley knew he was required to register under Kansas law, and "SORNA’s criminal provision is not a specific intent law.... There is no language requiring specific intent or a willful failure to register such that he must know his failure to register violated federal law.”
Gould,
. The Attorney General published interim regulations on February 28, 2007. See 28 C.F.R. § 72 (2007). The regulations state that SOR-NA applies "to all sex offenders, including sex offenders convicted of the offense for which registration is required prior to the enactment of that Act,” and make no exception for the period prior to the issuance of the interim regulations. Id. § 72.3.
. Whaley was charged with failure to register after the interim regulation on retroactivity was published.
