A joint defense agreement is a written contract that lets separately represented parties — co-defendants, co-targets of an investigation, or companies facing related regulatory actions — share confidential legal information with each other’s lawyers without destroying attorney-client privilege or work product protection. It puts the common interest doctrine into enforceable form, so that coordinated strategy and shared memos stay shielded from the opposing side instead of becoming discoverable the moment they leave your lawyer’s office.
The arrangement sounds simple. In practice, whether it holds up depends almost entirely on how the agreement is drafted and how carefully the group behaves after signing it.
What a Joint Defense Agreement Protects
Sharing privileged information with anyone outside the attorney-client relationship normally waives the privilege, and once waived, the opposing side can compel production of what was shared. The common interest doctrine is an exception: when two or more parties share a genuine legal interest, communications among their lawyers, and between lawyers and each other’s clients, stay privileged even though they cross the usual boundary.
A JDA extends two distinct shields to information shared inside the group. Attorney-client privilege covers confidential communications between a lawyer and client made for the purpose of legal advice. Work product protection covers materials prepared by a lawyer in anticipation of litigation, including mental impressions, legal theories, and trial strategies. Both travel with the information when it moves within the JDA group. A litigation memo your lawyer sends to a co-defendant’s lawyer does not lose its work product status in transit.
The protection has a condition attached. The sharing must be for the purpose of advancing the joint legal effort. Casual business discussions, financial planning, or operational conversations between JDA members do not automatically pick up privilege just because an agreement exists in the background.
When a JDA Is Valid
Courts read the common interest doctrine narrowly. A JDA that misses one of the baseline requirements will not shield anything, no matter how formal it looks.
- A shared legal interest. Co-defendants in the same lawsuit, targets of the same government investigation, or companies responding to related regulatory actions qualify. A joint venture or shared commercial goal, standing alone, does not.
- Intent to further the joint effort. Every communication passed under the JDA must be made to advance the common legal strategy. Information exchanged for unrelated business reasons sits outside the privilege even between JDA members.
- An actual or anticipated legal threat. This is where jurisdictions diverge. Some federal circuits require pending or reasonably anticipated litigation; others, including the Seventh Circuit, have extended the doctrine to purely transactional contexts where parties face a shared legal concern without active litigation.
- Attorney involvement. Communications within the group generally need to involve or be directed by counsel. Two JDA members talking without lawyers present may not receive protection, even on topics tied to the common defense.
Oral JDAs technically work in some jurisdictions, but the party claiming privilege bears the burden of proving it existed. A signed document makes that burden much easier to carry if the other side challenges the protection.
What a Written JDA Should Spell Out
A well-drafted agreement does more than declare that a common interest exists. It anticipates the specific ways the arrangement can fracture and addresses them in advance.
Scope and Confidentiality
Define exactly what legal matter the agreement covers and limit the use of shared materials to that matter. Vague scope language invites later disputes about whether a given communication was really inside the JDA. Specify the sharing format — encrypted email, a secure data room, in-person meetings — and restrict who within each party’s organization can access shared information.
No Attorney-Client Relationship Disclaimer
Without a clear disclaimer, a JDA member may later argue that another party’s lawyer effectively became their lawyer too, which can disqualify that attorney from the case entirely. The clause should state that each lawyer represents only their own client and that no attorney-client relationship forms with any other JDA member. ABA Formal Opinion 95-395 confirms that a JDA does not by itself create an attorney-client relationship, but it also notes that lawyers will “almost certainly” take on fiduciary obligations to the other parties, meaning they must keep shared confidences even without a formal relationship.1American Bar Association. ABA Formal Opinion 95-395
Advance Conflict Waivers
Alliances fracture. If one member later becomes adverse to another, the shared confidences could disqualify a lawyer from continuing to represent their original client. An advance waiver has all parties agree upfront that no member will seek to disqualify another member’s counsel based on information learned through the JDA. Federal courts have upheld these waivers when the agreement explicitly states that counsel has no duties to non-client parties and that the agreement cannot be used as a basis for disqualification in future litigation.
Adverse Co-Party Procedures
The agreement should spell out what happens if a member decides to cooperate with the government or otherwise turns against the group. A common approach requires the departing member to give immediate written notice to all remaining participants as soon as cooperation discussions begin. Some JDAs also include a cross-examination provision, allowing lawyers to use information the departing member previously shared to impeach that person if they later testify against the group.
If a Member Cooperates With the Government
This is where a JDA faces its hardest test. In criminal cases and government investigations, the pressure to cooperate with prosecutors can be severe, and a member who flips has already absorbed the strategies and confidences of everyone else in the group.
The legal rule helps the remaining members: one party to a JDA cannot unilaterally waive the privilege for everyone else. Shared communications stay privileged as to the other members even after someone leaves. The departing member can share their own independent information with prosecutors but cannot hand over communications that were shared under the JDA umbrella.
The practical reality is messier. A cooperating witness may testify about the substance of what they learned without directly producing the privileged documents, and prosecutors can use leads from a cooperator to develop independent evidence. That is why detailed notice and cross-examination provisions matter so much on paper. A JDA that does not address cooperation scenarios has a serious gap.
Inadvertent Disclosure and Clawback
In large cases, JDA members may collectively produce hundreds of thousands of documents during discovery, and privileged material sometimes ends up in the wrong hands. Federal Rule of Evidence 502(b) provides a safety net: an inadvertent disclosure does not waive the privilege if the holder took reasonable steps to prevent it and acted promptly to fix the error once discovered.2Legal Information Institute. Federal Rules of Evidence Rule 502 – Attorney-Client Privilege and Work Product Limitations on Waiver
A JDA should include its own clawback procedure that works alongside Rule 502. The standard approach gives the producing party a set number of business days to demand return of an inadvertently produced document, provide a privilege log explaining the basis for protection, and require the receiving party to return or destroy all copies. If the receiving party objects, the dispute goes to the court. During that review period, neither side can use the contested document.3United States District Court, District of Utah. Clawback Agreements and Federal Rule of Evidence 502
To give clawback protections the broadest reach, including against third parties in other litigation, the parties should ask the court to enter the agreement as an order under Rule 502(d). A private agreement between parties only binds those parties. A court order binds everyone.
Where JDAs Break Down
Implied Attorney-Client Relationships
Even with a clear disclaimer, some courts have found that a JDA can create an implied attorney-client relationship between a lawyer and a non-client JDA member. The Ninth Circuit has recognized this possibility where a non-client reasonably believed they were receiving legal representation. If a court agrees, the lawyer may be disqualified from representing their original client in any matter adverse to the non-client member. The safest approach is to reinforce the boundary in practice: lawyers avoid giving legal advice directly to non-client members and route all substantive communications through each member’s own counsel.
The Crime-Fraud Exception
The common interest privilege, like attorney-client privilege generally, does not protect communications made in furtherance of a crime or fraud. If a member is using the agreement as cover to coordinate illegal activity rather than to mount a legitimate legal defense, the privilege can be pierced. This exception applies even if other members of the JDA are acting in good faith. Courts examine the specific communications at issue, and a showing that the privilege is being abused can unravel protection for the entire group.
Narrow Construction
Courts treat the common interest doctrine as an exception to the general rule that sharing with third parties waives privilege, and exceptions get read narrowly. If there is any ambiguity about whether a communication was made in furtherance of the joint legal effort, courts tend to rule against privilege. Keeping records of which communications were shared, when, and for what purpose makes defending the privilege far easier if it is challenged.
Ending the Agreement
A JDA typically ends in one of three ways: the underlying matter is resolved through judgment or settlement, a party formally withdraws, or all parties agree to dissolve the arrangement. The agreement should require any withdrawing party to give immediate written notice to all remaining members.
The critical point is that confidentiality obligations survive termination. Information shared under a JDA does not lose its protection just because the agreement ends. Every JDA should state explicitly that no party may use or disclose previously shared information against any other party in future proceedings. Without a clear survival clause, a former member could argue that the end of the agreement freed them from confidentiality obligations, creating exactly the exposure the JDA was meant to prevent.