On October 2, 1937 the Marijuana Tax Act was enacted. On this same day, a man named Samuel R. Caldwell was arrested by federal agents for selling Marijuana to Moses Baca, who was also arrested.

Is this still allowed, whether federally or on the state level? Can you be arrested the day a law is enacted?

1 Answer 1


The Act was enacted on August 2, 1937. Pub. 238, 75th Congress, 50 Stat. 551

It had an effective date of October 1, 1937, specified at Sec. 17:

This Act shall take effect on the first day of the second month after the month during which it is enacted.

As soon as a law defining a crime is in effect, you can be arrested for that crime.

Calder v. Bull, 3 U.S. 386 (1798) sets out the limits on ex post facto laws, as prohibited by clause 3 of Article I, Section 9 of the Constitution ("No Bill of Attainder or ex post facto Law shall be passed").

A law is prohibited if it "makes an action done before the passing of the law and which was innocent when done, criminal and punishes such action." Thus, the limit is a strict limit against retroactivity, but a law can become effective immediately.

Justice Story, in In re Richardson et al. 2 Story, 571 (1843) wrote:

[...] it appears to me, that in all cases of public laws, the very time of the approval constitutes, and should constitute, the guide as to the time, when the law is to have its effect [...]

The legislature have it in their power to prescribe the very moment, in futuro, after the approval, when a law shall have effect.

  • It looks like the Wikipedia article has incorrect information. It says the law was "enacted" on Oct. 2, but I see that's not the case. Thank you K-C, answer accepted!
    – Cannabijoy
    Commented Jan 14, 2017 at 5:14
  • This raises an interesting question. Suppose a legislature passes a law which is to have immediate effect, and the governor signs it immediately. Shortly thereafter, Jane is caught violating the law, but circumstances are such that she could not reasonably have been aware of its passage. (Suppose she's in a remote area and has no radio, phone, or contact with others.) Can she be convicted? Commented Jan 14, 2017 at 5:55
  • Ignorance of the law is not a defence. Jane gets busted and convicted, assuming evidence sufficient.
    – user4657
    Commented Jan 14, 2017 at 6:09
  • 2
    @NateEldredge Yes. While it might appear that the unfairness caused by ex post facto laws is the same unfairness caused by ignorance of existing law, Shevlin-Carpenter Co. v. Minnesota 218 U.S. 57 (1910) held that "Innocence cannot be asserted as to an action which violates existing law, and ignorance of law will not excuse."
    – K-C
    Commented Jan 14, 2017 at 6:09
  • 2
    @NateEldredge However, there are certain circumstances where due process trumps the "ignorance of the law is no excuse" principle. Lambert v. California, 355 U.S. 225 (1957) concerned a law which punished wholly passive failure to act under circumstances that don't on their own alert the doer to the consequences of his deed (criminals visiting the city for more than five days had to register). This law was held to violate the Due Process clause of the 14th Amendment.
    – K-C
    Commented Jan 14, 2017 at 6:18

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