Where this sits
- Chapter 4.5.
- Division of Workers' Compensation
- Subchapter 2. Workers' Compensation Appeals Board--Rules and Practice Procedure
- Article 4. Conduct of Parties, Attorneys and Non-Attorney Representatives
The regulation, as printed
(a) On its own motion or upon the filing of a petition pursuant to rule 10510, the Workers' Compensation Appeals Board may order payment of reasonable expenses, including attorney's fees and costs and, in addition, sanctions as provided in Labor Code section 5813. Before issuing such an order, the alleged offending party or attorney must be given notice and an opportunity to be heard. In no event shall the Workers' Compensation Appeals Board impose a monetary sanction pursuant to Labor Code section 5813 where the one subject to the sanction acted with reasonable justification or other circumstances make imposition of the sanction unjust. (b) Bad faith actions or tactics that are frivolous or solely intended to cause unnecessary delay include actions or tactics that result from a willful failure to comply with a statutory or regulatory obligation, that result from a willful intent to disrupt or delay the proceedings of the Workers' Compensation Appeals Board, or that are done for an improper motive or are indisputably without merit. Violations subject to the provisions of Labor Code section 5813 shall include but are not limited to the following: (1) Failure to appear or appearing late at a conference or trial where a reasonable excuse is not offered or the offending party has demonstrated a pattern of such conduct. (2) Filing a pleading, petition or legal document unless there is some reasonable justification for filing the document. (3) Failure to timely serve documents (including but not limited to medical reports and medical-legal reports) as required by the rules of the Workers' Compensation Appeals Board, or the Administrative Director, where the documents are within the party's possession or control, unless that failure resulted from mistake, inadvertence or excusable neglect. (4) Failing to comply with the Workers' Compensation Appeals Board's Rules of Practice and Procedure, with the regulations of the Administrative Director, or with any award or order of the Workers' Compensation Appeals Board, including an order of discovery, which is not pending on reconsideration, removal or appellate review and which is not subject to a timely petition for reconsideration, removal or appellate review, unless that failure results from mistake, inadvertence, surprise or excusable neglect. (5) Executing a declaration or verification to any petition, pleading or other document filed with the Workers' Compensation Appeals Board: (A) That: (i) Contains false or substantially false statements of fact; (ii) Contains statements of fact that are substantially misleading; (iii) Contains substantial misrepresentations of fact; (iv) Contains statements of fact that are made without any reasonable basis or with reckless indifference as to their truth or falsity; (v) Contains statements of fact that are literally true, but are intentionally presented in a manner reasonably calculated to deceive; and/or (vi) Conceals or substantially conceals material facts; and (B) Where a reasonable excuse is not offered or where the offending party has demonstrated a pattern of such conduct. (6) Bringing a claim, conducting a defense or asserting a position: (A) That is: (i) Indisputably without merit; (ii) Done solely or primarily for the purpose of harassing or maliciously injuring any person; and/or (iii) Done solely or primarily for the purpose of causing unnecessary delay or a needless increase in the cost of litigation; and (B) Where a reasonable excuse is not offered or where the offending party has demonstrated a pattern of such conduct. (7) Presenting a claim or a defense, or raising an issue or argument, that is not warranted under existing law -- unless it can be supported by a non-frivolous argument for an extension, modification or reversal of the existing law or for the establishment of new law -- and where a reasonable excuse is not offered or where the offending party has demonstrated a pattern of such conduct. In determining whether a claim, defense, issue or argument is warranted under existing law, or if there is a reasonable excuse for it, consideration shall be given to: (A) Whether there are reasonable ambiguities or conflicts in the existing statutory, regulatory or case law, taking into consideration the extent to which a litigant has researched the issues and found some support for its theories; and (B) Whether the claim, defense, issue or argument is reasonably being asserted to preserve it for reconsideration or appellate review. This subdivision is specifically intended not to have a “chilling effect” on a party's ability to raise and pursue legal arguments that reasonably can be regarded as not settled. (8) Asserting a position that misstates or substantially misstates the law, and where a reasonable excuse is not offered or where the offending party has demonstrated a pattern of such conduct. (9) Using any language or gesture at or in connection with any hearing, or using any language in any pleading or other document: (A) Where the language or gesture: (i) Is directed to the Workers' Compensation Appeals Board, to any of its officials or staff or to any party (or the attorney or non-attorney representative for a party); and (ii) Is patently insulting, offensive, insolent, intemperate, foul, vulgar, obscene, abusive or disrespectful; or (B) Where the language or gesture impugns the integrity of the Workers' Compensation Appeals Board or its commissioners, judges or staff.
The statute above this rule
Every regulation names the Labor Code it was written under. This is where the two halves of the law meet.
ImplementsLabor Code § 5906
Authority and history
Note: Authority cited: Sections 133, 5307, 5309 and 5708, Labor Code. Reference: Sections 4903.6(c), 5701, 5703.5, 5706, 5708, 5813 and 5906, Labor Code.
1. Renumbering of former section 10561 to section 10421, including amendment of section and Note, filed 12-17-2019; operative 1-1-2020. Submitted to OAL for printing only pursuant to Government Code section 11351 (Register 2019, No. 51).
What panels did with this rule
Released decisions that named § 10421, with the passage each turned on. A panel decision persuades; it does not bind.
- ADJ17889413 · 2026-06-26 · Oxnard District Office8 CCR § 10421
Determinative passage · p.2assist in the preparation of petitions and other documents filed with the Workers' Compensation Appeals Board (WCAB), filing a document that misrepresents facts and law, whether or not it was prepared with the assistance of AI, constitutes prima facie evidence of sanctionable conduct under Labor Code section 58132 and WCAB Rule 10421. (Lab. Code, § 5813; Cal. Code Regs., tit. 8, § 10421.)
The tribunal applied this standard to impose sanctions on former defense counsel for filing a Petition for Reconsideration with AI-generated misrepresentations.
Official decision · page 2 → - ADJ16635028 · 2026-06-26 · Long Beach District Office8 CCR § 10421
Determinative passage · p.11IV. With respect to the issue of sanctions, WCAB Rule 10421(b)(1) provides the following:
Official decision · page 11 → - ADJ19334270 · 2026-06-05 · San Bernardino District Office8 CCR § 10421
Determinative passage · p.4II. WCAB Rule 10305(c) defines "Appear" as "to act on behalf of any party." Section 5700 clarifies that an appearance may be by the party or their agent. (See Cal. Code Regs., tit. 8, § 10752(a).) Section 5813 authorizes the WCJ to impose sanctions, attorney's fees, and costs for "bad- faith actions or tactics that are frivolous or solely intended to cause unnecessary delay." (Lab. Code, § 5813(a).) The order of sanctions can be made "after written application by the party seeking sanctions or upon the appeal board's own motion." (Lab. Code, § 5813(b).) In order for the WCJ to impose sanctions and costs, the alleged offending party or attorney must be given notice and an opportunity to be heard. (Cal. Code Regs., tit. 8, § 10421(a); see also Cal. Code Regs., tit. 8, § 10832(a)(3).) Bad faith actions or tactics that are frivolous or solely intended to
The WCJ must provide notice and an opportunity to be heard before imposing sanctions; here, the record did not establish that applicant's attorney received notice or had an opportunity to be heard.
Official decision · page 4 → - ADJ12703817 · 2026-06-05 · Pomona District Office8 CCR § 10421
Determinative passage · p.6Cal.App.4th 294, 302.) WCAB Rule 10421, subdivision (b), authorizes sanctions for a party who has committed "[b]ad faith actions or tactics that are frivolous or solely intended to cause unnecessary delay including actions or tactics that result from willful failure to comply with a statutory or regulatory obligation, that result from a willful intent to disrupt or delay the proceedings of the Workers' Compensation Appeals Board, or that are done for an improper motive or are indisputably without merit." (Cal. Code Regs., tit. 8, § 10421(b).)
Admonishment of defendant's conduct regarding discovery orders.
Official decision · page 6 → - ADJ11096892 · 2026-04-24 · San Francisco District Office8 CCR § 10421
Determinative passage · p.3Pursuant to section 5813(a), the Workers' Compensation Appeals Board has the discretionary power to order the payment of sanctions for "bad-faith actions or tactics which are frivolous or solely intended to cause unnecessary delay." (Lab. Code, § 5813(a).) Bad-faith actions or tactics are defined as "actions or tactics that result from a willful failure to comply with a statutory or regulatory obligation, that result from a willful intent to disrupt or delay the proceedings of the Workers' Compensation Appeals Board, or that are done for an improper motive or are indisputably without merit" and include "[b]ringing a claim, conducting a defense or asserting a position: (A) That is: (i) Indisputably without merit; (ii) Done solely or primarily for the purpose of harassing or maliciously injuring any person; and/or (iii) Done solely or primarily for the purpose of causing unnecessary delay or a needless increase in the cost of litigation...." (Cal. Code Regs., tit. 8, § 10421(b)(6).)
The WCJ did not abuse discretion in declining to impose sanctions for lien claimant's failure to appear.
Official decision · page 3 → - ADJ10371658 · 2026-04-24 · Van Nuys District Office8 CCR § 10421
Determinative passage · p.6In his Report, the WCJ further stated that: Although defendants' arguments were ultimately found to be incorrect, there is reasonable ambiguity in the regulations with respect to both whether settlement interpreting costs are allowed at all, as well as the amount. There is no binding en banc or appellate opinion to make defendants' position on this issue unwarranted.... Section 10421(6)(7), which defines sanctionable "bad faith actions or tactics" under Labor Code section 5813 as including presenting a claim or a defense, or raising an issue or argument, that is not warranted under existing law. Also mitigating against a finding of sanctionable conduct are the reasonable ambiguities in the law, which are to be considered under Section 10421(6)(7)(A), and the impression that defendants have preserved and raised this issue in good faith for the purpose of adjudication, which is to be considered under Section 1042l(b)(7)(B).
The WCAB found that the ambiguity in the law and the lack of binding authority meant defendant's conduct was not sanctionable.
Official decision · page 6 → - ADJ19292947 · 2026-04-10 · San Jose District Office8 CCR § 10421
Determinative passage · p.4Also relevant is WCAB Rule 10421, subdivision (b), which authorizes sanctions for a party who has committed "[b]ad faith actions or tactics that are frivolous or solely intended to cause unnecessary delay including actions or tactics that result from willful failure to comply with a statutory or regulatory obligation, that result from a willful intent to disrupt or delay the proceedings of the Workers' Compensation Appeals Board, or that are done for an improper motive or are indisputably without merit." (Cal. Code Regs., tit. 8, § 10421(b).)
Applied to determine whether defendant's delay in payment constituted bad faith warranting sanctions and attorney's fees.
Official decision · page 4 → - ADJ16423182 · 2026-02-23 · Los Angeles District Office8 CCR § 10421
Determinative passage · p.10Before issuing such an order, "the alleged offending party or attorney must be given notice and an opportunity to be heard." (Cal. Code Regs., tit. 8, § 10421(a) bold and italics added for emphasis.) WCAB Rule 10421, subdivision (b), authorizes sanctions for a party who has committed "[b]ad faith actions or tactics that are frivolous or solely intended to cause unnecessary delay including actions or tactics that result from willful failure to comply with a statutory or regulatory obligation, that result from a willful intent to disrupt or delay the proceedings of the Workers' Compensation Appeals Board, or that are done for an improper motive or are indisputably without merit." (Cal. Code Regs., tit. 8, § 10421(b).) Subdivision (b) provides a comprehensive but non-exclusive list of actions that could be subject to sanctions. As applicable here, violations subject to sanctions, pursuant to WCAB Rule 10421(b), include:
The WCJ cited bad faith and frivolous litigation as grounds for sanctions but did not create an adequate record to support these findings.
Official decision · page 10 →
Rules beside this one
Article 4. Conduct of Parties, Attorneys and Non-Attorney Representatives — regulations rarely stand alone, and the answer is often two sections away.
- § 10412Proceedings and Decisions After Venue Change. [Repealed]
- § 10414Declaration of Readiness to Proceed. [Renumbered]1 decisions
- § 10415Declaration of Readiness to Proceed to Expedited Hearing. [Repealed]
- § 10416Objection to Declaration of Readiness to Proceed. [Renumbered]
- § 10417Walk-Through Documents. [Renumbered]
- § 10420Setting the Case. [Renumbered]