Joint Defense When Your Lead Vendor Is Sued Too
When a TCPA complaint names both a company and the vendor that sent its messages, the two often want the same outcome, and they often point at each other. Sharing privileged information between them can help or can destroy the privilege, depending on whether a real common legal strategy exists and whether the arrangement is documented. A joint defense agreement is the usual tool, and counsel have to decide before the first shared call whether the companies’ interests are aligned enough to use one.
Why do seller and vendor end up as co-defendants?
Because the plaintiff can sue whoever called or texted and whoever’s goods were advertised. A seller and its marketing vendor often face the same claims on the same messages, with the same consent records at issue. Both want to show consent, both want to attack class certification, and both have reasons to avoid a record that suggests the messages were sent carelessly.
That alignment is real but partial. The vendor usually holds the technical data: the sending logs, the platform settings, the source of the numbers. The seller usually holds the customer relationship and the consent forms. Each depends on the other for proof, so sharing happens, and each has reason to say the other was responsible, so sharing needs care.
How does the common interest doctrine protect shared communications?
It is an exception to the usual rule that sharing privileged material with an outsider waives the privilege. The Ninth Circuit explained in In re Pacific Pictures Corp., 679 F.3d 1121 (9th Cir. 2012), that the common-interest or joint-defense rule “is an exception to ordinary waiver rules designed to allow attorneys for different clients pursuing a common legal strategy to communicate with each other,” and not a separate privilege.
The court set limits in the same opinion. “However, a shared desire to see the same outcome in a legal matter is insufficient to bring a communication between two parties within this exception.” And the parties must act under an agreement. In the court’s words, they “must make the communication in pursuit of a joint strategy in accordance with some form of agreement,” which may be written or unwritten, as the opinion puts it.
In plain terms, it isn’t enough that the seller and vendor both hope to win. They need a joint legal strategy, and an agreement that says so. I would put the agreement in writing, because “unwritten” is a description of what a court may accept, not of what you want to defend after a motion to compel.
California law has a related protection. A confidential communication between client and lawyer includes one that discloses information to “those to whom disclosure is reasonably necessary for the transmission of the information or the accomplishment of the purpose for which the lawyer is consulted,” under Evidence Code § 952. And a disclosure in confidence “when disclosure is reasonably necessary for the accomplishment of the purpose for which the lawyer” was consulted “is not a waiver of the privilege,” according to § 912(d). Which body of privilege law applies depends on the forum and the claims, so counsel should confirm it for the case.
What should a joint defense agreement say?
At a minimum, it should state the common legal interest in plain terms, such as defending the plaintiff’s TCPA claims over the identified campaign. It should say that shared communications remain privileged and confidential, that sharing doesn’t waive any privilege, and that no party gets access to another’s separate privileged material. It should say who may attend joint meetings, how documents are marked, and what happens to shared material if one party withdraws.
Equally important is what it should not say. It should not create an attorney-client relationship between one company’s lawyers and the other company. It should not oblige either side to share anything. And it should state that the parties may take adverse positions against each other, including a cross-claim, without that being a breach, because the interests are common only in part. A joint defense agreement that is silent on those points can cause trouble when the seller later wants to sue the vendor, or the reverse.
When are the interests too far apart?
When the central dispute between the two companies is the thing the plaintiff is attacking. If the seller’s defense is that the vendor sent messages in violation of the contract and without authority, and the vendor’s defense is that the seller approved every campaign, the two are in conflict on the facts that matter most. Sharing strategy then risks giving the other side material it will use in a later claim over indemnity.
Lawyers face an ethics problem as well. Under California’s Rule of Professional Conduct 1.7, a lawyer may not represent a client without informed written consent where the representation is directly adverse to another client or where there is a real risk the representation will be materially limited by relationships with another client. One firm representing both a seller and its vendor on a claim in which each may blame the other is the scenario that rule exists to address. In nearly all cases I’d expect separate counsel for each company, with a joint defense agreement connecting them for the parts of the case where they agree.
| Question | If the answer is yes | If the answer is no |
|---|---|---|
| Is there a joint legal strategy on the plaintiff’s claims? | A joint defense agreement may fit | Limit sharing to what the law requires |
| Does each side need the other’s records to prove consent? | Plan a controlled exchange of documents | Each can defend alone |
| Is a cross-claim or indemnity dispute likely? | Use separate counsel and a narrow agreement | Broader cooperation is lower risk |
| Do the companies agree on the facts about who authorized the messages? | Cooperation is safer | Share less and document more |
How do the two companies work together without waiving anything?
Through lawyers, and through a defined channel. Business people at the seller and the vendor will want to talk directly, and they should be told not to discuss the case, the other side’s fault, or what the lawyers think. A privilege can be lost in a casual call between account managers, and a text exchange between them is discoverable. Route the conversation through counsel, or have counsel present.
Keep two kinds of material apart. Facts, such as the logs, the consent forms, and the platform settings, are not privileged just because lawyers handled them, and each side may need to produce them. Legal analysis, such as strategy about class certification or the consent argument, is what the agreement protects. A good protocol labels shared analysis clearly, keeps a list of who received it, and returns or destroys it if one company drops out.
Expect disagreements. The vendor may think the seller’s consent forms are weak, and the seller may think the vendor’s platform settings caused the problem. Say so inside the privilege, not in a letter that the plaintiff will later see. And if the disagreement turns into a dispute over indemnity, stop sharing strategy and let the separate lawyers handle it.
What to do in the first weeks after both companies are served
- Decide whether to tender the defense to the vendor, or the reverse, under the contract, and send any notice the contract requires.
- Retain separate counsel for each company and have the lawyers confer before the companies share anything.
- Sign a written common interest agreement before exchanging privileged material.
- Issue litigation holds at both companies, because the vendor’s logs may decide the case.
- Keep a log of each item shared, with its date and recipient.
The firm’s TCPA defense lawyers page describes how these claims move through court. For related reading, see the earlier posts on TCPA vendor contracts and indemnity and on when a seller is liable for a vendor’s calls.
Questions defendants ask about sharing with a co-defendant
Can the company’s lawyer also represent the vendor?
Rarely. The risk of conflict is high when each may blame the other, and any joint representation needs informed written consent after counsel has considered whether the representation is appropriate at all.
Does an email to the vendor’s lawyer stay privileged?
It can, if the common interest requirements are met and the sharing is within the agreement. Without them, the communication may be treated as a disclosure to a third party.
What if the vendor refuses to preserve its logs?
Send a written preservation demand citing the contract and the pending claim, and raise it with counsel at once, since the logs may be unrecoverable later.
Does a joint defense agreement stop us from suing the vendor later?
It shouldn’t, if it is drafted to say the parties may take adverse positions. Check the language before signing.
Defending a TCPA claim alongside a vendor
If your company and its vendor have both been sued over the same calls or texts, how the two defenses are coordinated, and what is shared between them, will affect the outcome. Rosenberger + Kawabata represents businesses defending TCPA lawsuits and class actions through its business litigation practice, including claims involving vendor and seller co-defendants. Contact Rosenberger + Kawabata online for a confidential consultation, or call (310) 894-6921.
Sources
The California statutes are Evidence Code § 952 and § 912, and the Telephone Consumer Protection Act is at 47 U.S.C. § 227. The professional conduct rule is California Rule of Professional Conduct 1.7.
The court decision is In re Pacific Pictures Corp., 679 F.3d 1121 (9th Cir. 2012).
This post is general information about the Telephone Consumer Protection Act and related laws as of September 22, 2026. It is not legal advice, and reading it does not create an attorney-client relationship. Courts and the FCC change the rules in this area often, and the outcome of any claim depends on its facts. Past results do not guarantee future outcomes.