# Montana SB 508: Generally revise driving under the influence laws for THC levels in drivers under 21

Montana SB 508, Generally revise driving under the influence laws for THC levels in drivers under 21, is a 69th Legislature, Regular Session (2025) Senate bill sponsored by Willis Curdy (Democrat); status signed, last action 2025-05-08 (Chapter Number Assigned) (as of 2026-10-12).

- Canonical: https://policyrisk.com/state-bill/MT-SB508-2025
- As of: 2026-10-12
- Plain-text twin of the page above; the HTML and this file carry the same facts.

## Facts
- Bill: Montana SB 508
- State: Montana
- Session: 69th Legislature, Regular Session (2025)
- Title: Generally revise driving under the influence laws for THC levels in drivers under 21
- Status: signed
- Chamber: Senate
- Introduced: 2025-02-25
- Last action: 2025-05-08, Chapter Number Assigned
- Sponsor: Willis Curdy (Democrat)
- Cosponsors: 1
- Subjects: Alcohol, Law Enforcement, Motor Vehicles
- Touches household money: no
- Roll calls: 4 (209 yes, 89 no in all)
- Economic provisions PRIA read: 1

## Summary

No summary available.

## Bill overview: provisions PRIA read

- Under-21 drivers: any THC equals DUI: cost, low. In Montana, if you are under 21, any detectable THC means you are driving under the influence. Inactive THC metabolites do not count. Testing can be by blood or another bodily substance. This applies when you drive or are in actual physical control of a vehicle.

## Sponsors and cosponsors

- Sponsor: Willis Curdy (Democrat), Senate
- Cosponsor: Steven Kelly (Republican), House

## Roll call votes

| Date | Chamber | Motion | Result | Yes | No | Other |
| --- | --- | --- | --- | --- | --- | --- |
| 2025-04-11 | House | Do Concur | pass | 61 | 39 |   |
| 2025-04-11 | House | Do Concur | pass | 62 | 37 |   |
| 2025-03-06 | Senate | Do Pass | pass | 44 | 6 |   |
| 2025-03-06 | Senate | Do Pass | pass | 42 | 7 |   |

## Actions (23)

- 2025-05-08: Chapter Number Assigned (Senate)
- 2025-05-05: Signed by Governor (Senate)
- 2025-04-25: Transmitted to Governor (Senate)
- 2025-04-25: Signed by Speaker (House)
- 2025-04-21: Signed by President (Senate)
- 2025-04-14: Returned from Enrolling (Senate)
- 2025-04-11: Sent to Enrolling (Senate)
- 2025-04-11: 3rd Reading (House)
- 2025-04-11: 2nd Reading (House)
- 2025-04-09: Committee Report (House)
- 2025-04-09: Committee Executive Action (House)
- 2025-04-07: Hearing (House)
- 2025-03-17: 1st Reading (House)
- 2025-03-17: Referred to Committee (House)
- 2025-03-07: Transmitted to House (Senate)
- 2025-03-06: 3rd Reading (Senate)
- 2025-03-06: 2nd Reading (Senate)
- 2025-03-04: Committee Report (Senate)
- 2025-03-03: Committee Executive Action (Senate)
- 2025-03-03: Hearing (Senate)
- 2025-02-26: Referred to Committee (Senate)
- 2025-02-26: 1st Reading (Senate)
- 2025-02-25: Introduced (Senate)

## Bill text

- Enrolled, 2025-04-15: [PDF](https://docs.legmt.gov/download-ticket?ticketId=ec06f627-6134-4892-8d96-bf8f59d319f0)
- Introduced, 2025-02-25: [PDF](https://docs.legmt.gov/download-ticket?ticketId=59129659-6565-4901-8e06-1b1b801e646a)

## Related bills

- SB 437: Revise definition of sex in Montana law (signed)
- HB 831: Increase elderly homeowner and renter income tax credit (vetoed)
- HB 628: Revise early literacy targeted intervention laws (vetoed)
- SB 410: Provide for Montana genomic security act (vetoed)
- SB 424: Revising the disabled veteran property tax assistance program (vetoed)
- SB 422: Generally revise laws relating to insurance coverage relating to cancer (vetoed)

## Sources
- [Enrolled (PDF)](https://docs.legmt.gov/download-ticket?ticketId=ec06f627-6134-4892-8d96-bf8f59d319f0)
- [Introduced (PDF)](https://docs.legmt.gov/download-ticket?ticketId=59129659-6565-4901-8e06-1b1b801e646a)

## Related
- [SB 437: Revise definition of sex in Montana law](https://policyrisk.com/state-bill/MT-SB437-2025)
- [HB 831: Increase elderly homeowner and renter income tax credit](https://policyrisk.com/state-bill/MT-HB831-2025)
- [HB 628: Revise early literacy targeted intervention laws](https://policyrisk.com/state-bill/MT-HB628-2025)
- [SB 410: Provide for Montana genomic security act](https://policyrisk.com/state-bill/MT-SB410-2025)
- [SB 424: Revising the disabled veteran property tax assistance program](https://policyrisk.com/state-bill/MT-SB424-2025)
- [SB 422: Generally revise laws relating to insurance coverage relating to cancer](https://policyrisk.com/state-bill/MT-SB422-2025)
- [Montana bills](https://policyrisk.com/states/montana/bills)
- [Montana state hub](https://policyrisk.com/states/montana)
- [All state legislation](https://policyrisk.com/state-bills)

Source: PRIA, https://policyrisk.com/state-bill/MT-SB508-2025 (as of 2026-10-12).