The major-offense ladder
A first major offense — driving under the influence, refusing alcohol or drug testing, leaving the scene of an accident, using a CMV in the commission of a felony, driving with a revoked CDL, or causing a fatality through negligent operation — disqualifies you from CDL operation for one year (three years if the vehicle was placarded for hazmat at the time of the offense). A second major offense at any point in your career is a lifetime disqualification, with possible reinstatement after ten years if you complete a state-approved rehabilitation program.
Serious violations
Serious violations — speeding fifteen miles per hour or more above the limit, reckless driving, improper or erratic lane changes, following too closely, using a commercial vehicle in a fatality without negligence, driving without the proper class of CDL, driving without the CDL in your possession, violating a railroad-grade crossing rule — disqualify you for sixty days on the second conviction within three years and one hundred twenty days on the third within three years.
Out-of-service orders and railroad violations
Violating an out-of-service order while driving carries a separate ladder: ninety days minimum for a first violation, one to five years for a second, and three to five years for a third within ten years. Railroad-grade crossing violations specific to CDL holders include not slowing down enough to be able to stop, not stopping when required, and failing to leave enough room to clear the crossing on the far side — each carrying its own escalating penalty schedule.
For drivers preparing for CDL Disqualification Rules, additional context — including federal manual excerpts, employer hiring practices, and DOT medical guidance — is widely available from industry resources. Continue reading on a recommended industry resource for further detail. Always cross-check anything you read with the current edition of your state CDL manual, since enforcement guidance is updated periodically.