What Is California Labor Code §4610.6: IMR Decision Final?

The determination of the independent medical review organization shall be deemed to be the determination of the administrative director and shall be binding on all parties.

What is Labor Code 4610.6?

Section 4610.6 governs how Independent Medical Review is conducted and says the result is final and binding, except on narrow legal grounds.

Independent Medical Review, usually called IMR, decides a disputed medical treatment request after Utilization Review denies or changes it. A reviewer picked by the state looks only at whether the treatment is medically necessary. Once that reviewer decides, this section treats the decision as if the state's own administrative director made it. Neither a workers' compensation judge nor the Workers' Compensation Appeals Board may reach a different medical necessity call on their own.

This section applies to every injured worker and every employer in the state system. It does not ask who is right about pain or need. It asks whether the review itself followed the rules.

Can an IMR decision ever be challenged?

Yes, but only on 5 narrow grounds. The law presumes the decision is correct unless one of them is proven by clear and convincing evidence.

Section 4610.6(h) lists the only grounds for a successful challenge:

• The administrative director acted without power, or went beyond the power the law gives.
• The decision was procured by fraud.
• The reviewer had a material conflict of interest barred by Labor Code section 139.5.
• The decision resulted from bias based on race, national origin, ethnic group, religion, age, sex, sexual orientation, color, or disability.
• The decision rested on a plainly wrong fact, but only a fact within ordinary knowledge, not a fact that turns on expert medical opinion.

A simple disagreement with the medical outcome is not on this list. A challenge has to show a problem with the process or the reviewer, not just an unwelcome result.

How and when does a worker or employer file a challenge?

The challenge must be filed within 30 days of the determination, following strict rules set by regulation.

Section 4610.6(h) itself sets the 30-day clock, counted from the date the determination was mailed. 8 CCR Rule 10575 spells out how to file. The petition must use the right caption, name the case and IMR numbers, attach a copy of the determination and proof it was served, and state every fact and legal ground the petitioner wants the Board to consider. A ground left out of the petition is treated as given up. If the employer was separately disputing liability for a reason other than medical necessity when the determination issued, the petition waits until that other dispute is resolved.

What happens if the challenge succeeds or fails?

A successful challenge sends the dispute back for a new review by a different reviewer. An unsuccessful one leaves the original decision in place.

Under section 4610.6(i), if a judge or the Board rescinds the determination, the case goes back to the administrative director. The director then sends it to a different independent review organization. If no other organization is available, a different reviewer at the same organization handles it instead. No judge, the Board, or any higher court may simply swap in its own view of medical necessity.

How does this section connect to the rest of the IMR process?

Section 4610.6 is the last step in a chain that starts with Utilization Review and the request for IMR.

Utilization Review, defined in Labor Code 4610, is the insurer's first look at a treatment request. A denial or change can be appealed to IMR under Labor Code 4610.5, which sets the deadline to ask for that review, generally 30 days. This section governs what happens once the reviewer has the case, and how little room is left to challenge the result. This guide walks through all three stages together: asking for IMR, the reviewer's own timeline, and a petition under this section.

What should a worker do with an IMR decision?

Read the determination the day it arrives, save every page, and act fast if one of the 5 narrow grounds might apply.

Call (661) 273-1780 or use the contact form for a free consultation about an IMR determination or a denied treatment request. The firm reviews each matter on its own facts before taking it on. Have the determination, the proof of mailing, and the original Utilization Review decision ready.