Violation code

391.41A1-MCOOS

Medical (Certificate) - Operating a commercial motor vehicle while not medically certified as physically qualified to do so.

Driver Fitness1Non-OOS· SMS Appendix A v3.20

391.41A1-MCOOS is a Medical Certificate violation under 49 CFR §391.41A1-MCOOS. It falls in the Driver Fitness BASIC with a severity weight of 1/10. Nationally it was cited 609 times in the last five years, with an OOS rate of 24.0%.

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National roadside inspection stats

as of 6/20/2026

Inspections

608

that found this code

Violations

609

total written

OOS rate

24.0%

146 OOS

Source: FMCSA roadside inspection data (last 5 years). The OOS rate is the share of these violations that led the officer to mark the driver or vehicle out of service.

Violation group: Medical Certificate
Regulation §: 391.41A1-MCOOS
Severity weight: 1
Used in SMS: Yes
Status: Active
Updated: 6/20/2026

Last updated June 2026

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Notes

DSMS: Y | Comment: Added in 3.15 | Footnote: As of February 1, 2023, the violations in this table are included in SMS. Only violations cited on or after February 1 are included in SMS calculations. This update aligns SMS with how violations are being cited in a new software used for roadside inspections.

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Challenging 391.41A1-MCOOS through FMCSA DataQs

If this violation was written incorrectly, here are the angles trucking-safety managers use to contest it. Playbook: Driver Fitness.

Relevant 49 CFR49 CFR § 391.41

Physical qualifications for drivers

“A person shall not drive a commercial motor vehicle unless he/she is physically qualified to do so and, except as provided in §391.67, has on his/her person the original, or a copy, of a medical examiner's certificate that he/she is physically qualified to drive a commercial motor vehicle.”

Common ways to challenge this code

Medical certificate was valid and on file
A valid medical examiner's certificate was in the driver's qualification file and was either not produced at roadside or not properly recognized.
Evidence that wins
- ✓Copy of the valid medical examiner's certificate
- ✓Driver qualification file index
- ✓National Registry verification printout
CDL class / endorsement was correct for the operation
The driver's CDL class and endorsements were correct for the vehicle and cargo being operated.
Evidence that wins
- ✓Copy of the valid CDL with endorsements
- ✓Vehicle registration showing GVWR/configuration
- ✓Bill of lading or shipping papers showing cargo

Common pitfalls — avoid these

⚠A medical certificate that expired the DAY of inspection still fails — there is no grace period

⚡ Draft a challenge for 391.41A1-MCOOS →Read the DataQs guide first

More codes in Driver Fitness

Same BASIC category — ranked by national citation volume

View all Driver Fitness codes →

Other Medical Certificate codes

Codes under the same FMCSA violation group

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Frequently asked questions about 391.41A1-MCOOS

What does violation 391.41A1-MCOOS mean?

391.41A1-MCOOS is the FMCSA roadside-inspection violation code for "Medical (Certificate) - Operating a commercial motor vehicle while not medically certified as physically qualified to do so.", part of the Medical Certificate group, cited under 49 CFR §391.41A1-MCOOS.

What BASIC does 391.41A1-MCOOS affect?

391.41A1-MCOOS falls under the Driver Fitness BASIC in the FMCSA Safety Measurement System (SMS).

What is the CSA severity weight of 391.41A1-MCOOS?

391.41A1-MCOOS carries a severity weight of 1 out of 10. Higher weights indicate violations more closely tied to crash risk, and they count more toward a carrier's Driver Fitness score.

Is 391.41A1-MCOOS an out-of-service (OOS) violation?

No. 391.41A1-MCOOS is not an out-of-service violation, so on its own it does not trigger an out-of-service order at the roadside.

How many CSA points does 391.41A1-MCOOS add to a carrier's score?

The point contribution of 391.41A1-MCOOS depends on its severity weight (1/10) multiplied by a time weight of 3, 2, or 1 based on how recent the inspection is. You can calculate the exact contribution with the CSA points calculator.

Can 391.41A1-MCOOS be challenged through DataQs?

Yes. If you believe 391.41A1-MCOOS was recorded in error, you can file a Request for Data Review (RDR) through the FMCSA DataQs system with supporting evidence. A successful challenge can remove or correct the violation on your record.

Keep going

CSA points calculator How to challenge a violation Draft a DataQs letter for 391.41A1-MCOOS Driver Fitness BASIC Carrier CSA lookup CSA glossary