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Jefferson County, MO Public Conduct: Public Marijuana Use (2026)

Significant Restrictions
Compiled from the official code textEditor Martyn O'NeillLast verified August 2026

Key Facts

Prohibited act
Possessing or controlling marijuana
Exception
Authorized under RSMo §§195.005-195.425
Applies
Unincorporated Jefferson County only
Penalty
Up to $1,000 fine or 1 year jail
Related section
Paraphernalia ban, §205.210

Summary

Jefferson County makes it unlawful to possess or control marijuana anywhere in the unincorporated county unless the possession is authorized under Missouri's controlled-substances statutes, RSMo Sections 195.005 to 195.425, which include the state's licensed medical and adult-use marijuana program.

These county ordinances apply to unincorporated areas of Jefferson County. Incorporated cities within the county may have their own rules that take precedence over county-level regulations.

Except as authorized by Sections 195.005 to 195.425, RSMo., it is unlawful for any person to possess or have under his or her control marijuana as defined in Section 195.010, RSMo., in the unincorporated area of Jefferson County, Missouri.

Full Breakdown

425, RSMo. That cross-reference matters: Missouri's controlled-substances chapter, and the constitutional amendment it now incorporates, licenses medical marijuana patients and adults 21 and older to possess limited amounts, so someone who qualifies under state law and stays within state limits is not violating the county ordinance, while possession outside those state-authorized channels, including public consumption that exceeds licensed limits or occurs without state authorization, remains a county violation enforceable alongside any state charge. The ordinance does not distinguish public from private possession; it reaches marijuana anywhere in the unincorporated county, including on the street or in a park, making it the county's mechanism for citing public marijuana activity that falls outside the state-licensed framework. 210, which separately covers pipes, bongs, and related items used for controlled substances.

Violations & Fines

Violations of Section 205.200 are prosecuted as misdemeanors in Jefferson County Municipal Court by the County Municipal Prosecutor and are subject to the General Penalty, Section 100.030: a fine of up to $1,000, up to one year in the county jail, or both. Each day of unlawful possession can be charged as a separate offense under that general penalty provision.

Frequently Asked Questions

Does Missouri's legal marijuana law override this county ordinance?
Section 205.200 already builds in that exception: it only bans possession that is not authorized under RSMo Sections 195.005 to 195.425. A person possessing marijuana within the limits allowed under Missouri's medical or adult-use program is not violating the county ordinance; possession outside those limits is.
Can someone be cited for smoking marijuana in a county park?
Section 205.200 bans possessing or controlling marijuana anywhere in the unincorporated county, without a public/private distinction, so possessing it in a county park is covered the same as anywhere else unless the person is within state-authorized limits under RSMo Sections 195.005 to 195.425.
Does this county ordinance apply inside Arnold or Festus?
No. Chapter 205 of the Jefferson County Code governs only the unincorporated area. Arnold, Festus, De Soto and the county's other incorporated cities apply their own municipal codes and are also bound by the same underlying Missouri marijuana statutes.

Sources & Official References

Other rules in Jefferson County

All Jefferson County rules

Compare Jefferson County to another location·View the Missouri public conduct overview

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