JOINDER:  The More, The Merrier!

By:  Lauren M. Coleman, Associate Attorney, Bradford & Barthel, Concord.

As parties rush to settle their cases during the jolly days of settlement season, one key question to ask when settling cumulative trauma claims is whether all potential codefendants have been joined.

In this article, we will offer an overview of why joinder is necessary and why it is an important tool in our workers’ compensation toolbox.


Joinder is required to seek contribution from other employers and/or insurance carrier with liability during an alleged cumulative trauma period.  An employer should only pay for their share of liability, and joining codefendants reduces liability.

Labor Code §5500(a) limits liability for a cumulative trauma claim to one year immediately preceding either the date of injury, as determined pursuant to Section 5412, or the last date on which the employee was employed in an occupation exposing him or her to the hazards of the occupational disease or cumulative injury. If an employer does not have insurance coverage for the entire alleged cumulative trauma period, discovery should be completed as soon as possible to identify other codefendants to be joined.

It is also always easiest to obtain information directly from the source. To avoid the delay in discovery often caused by objections to subpoenas, etc., joining a codefendant forces them to provide information regarding their employment of the applicant and/or their insurance coverage.


The WCAB is generally hesitant to dismiss a defendant when it leaves the applicant without a defendant to provide benefits. In cases where a client has no coverage during an alleged cumulative trauma period, joining a codefendant who has coverage during the cumulative trauma period increases the odds of being dismissed from the case quickly. Evidence of insurance coverage can usually be easily obtained through an informal insurance coverage search on the WCIRB website.


Joinder is also important when for settlement of cases particularly when the parties may be considering strategic elections against codefendants. While it is best practice to have all defendants sign off on a settlement, this is not always possible as settlements are sometimes time sensitive at the urging of the applicant.

In these cases, it may be best to have the applicant issue an election, pursuant to Labor Code §5500(c), that allows for one defendant to resolve the case on behalf of all joined defendants, even if they do not review or sign the settlement documents. However, elections only apply to defendants joined as parties at the time of settlement. If additional defendants with liability during the cumulative trauma period exist but are not joined when the case settles, the settlement does not resolve their liability for the injury.


CCR §10382 allows the appeals board to order the joinder of additional parties not named in the application whose presence is necessary for the full adjudication of the case. Any person against whom any right to relief is alleged to exist may be joined as a defendant. This includes any employers or insurance carrier who might have liability during an alleged cumulative trauma. Given this low standard for joinder, when in doubt, join all potential codefendants and let them offer proof for why they should be dismissed as a party.

It is not uncommon for a span of multiple years to be plead as the cumulative trauma period. In this situation, discovery should be completed to identify codefendants in the entire alleged cumulative trauma period, even if the exact date of injury remains in dispute. When the date of injury is at issue, the WCAB may defer its decision regarding joinder until after the date of injury is determined, but the petition should still be filed as soon as information about potential codefendants is discovered.


As early as possible is generally best when filing a Petition for Joinder, but there is no set timeline for filing. The existence of other potential codefendants is often not obvious at the beginning of the claim and may be revealed through discovery including the deposition of the applicant and subpoenaed records. Once information is discovered about a potential codefendant, a Petition for Joinder should be filed as soon as the details of the new party are known, particularly the name and addresses of any additional employers or insurance carriers.

At the very least, all potential codefendants should be joined prior to the submission of a settlement of the case to ensure that all parties either sign the settlement documents or are jointly and severally bound by its terms through an election.

In rare cases, the WCAB has allowed for joinder in contribution proceedings after the case in chief has resolved. When a Petition for Contribution is timely filed, the WCAB has allowed for joinder of additional codefendants after settlement because Labor Code §5500(b) has no time limitation. See Lim v. Twelve Signs, Inc., 2014 Cal. Wrk. Comp. P.D. LEXIS 409.


A Petition for Joinder is required to join a party to a case. The Petition must be served on the party(ies) to be joined. Any order for joinder is subject to 10-day notice requirement and an opportunity for the party to be joined to be heard. This often results in judges setting a status conference upon receipt of a Petition for Joinder.

While technically only an allegation of liability is required to justify joinder of a party, it is good practice to offer some degree of proof of liability of the new party such as a printout from the WCIRB insurance coverage website or testimony from the applicant’s deposition confirming concurrent employment.

Only defendants joined prior to the first hearing may participate in discovery and the proceedings. If joined after the first hearing, Defendants can only conduct discovery to obtain information regarding the time, place, and duration of the alleged employment only.

They are otherwise limited from conducting any additional discovery until after the case in chief is resolved. For this reason, in cases where a client provides insurance coverage for a small portion of a cumulative trauma period, a Petition for Joinder should be filed before a hearing is requested to ensure that newly joined party can conduct discovery, participate in the proceedings, and, most importantly, be elected against.


Defenses against joinder are limited. The most common defense against joinder is a lack of employment and/or insurance coverage during the alleged cumulative trauma. However, since the burden of proof for joinder is very low, if discovery regarding the alleged employment is required, the WCAB will most often grant joinder of a defendant and issue a dismissal of the party upon petition if proof of lack of employment or insurance coverage is discovered.

Generally, all dismissals of parties are issued without prejudice, which allows for them to be re-joined in the event new evidence arises showing that a previously-dismissed party does actually have liability for the cumulative trauma claim.


Joinder is an important element of workers’ compensation defense, and should be strongly considered whenever a necessary party is discovered.

Lauren M. Coleman is an associate attorney at The Law Offices of Bradford & Barthel’s Concord office. Coleman has extensive experience in workers’ compensation defense, and aggressively defends against high-value, complex cases involving multiple injuries, employee/independent contractor disputes, contribution disputes, and Covid-19 claims. She also has prior experience working in employment and disability law.