Common Interest Privilege

Common Interest Privilege

Many attorneys may not fully understand the “common interest privilege,” which can significantly impact the success of a document and protect it from adversaries. This article will focus on joint defense common interest privilege as well as the specifics of common interest privilege in California and New York. In doing so, this essay will go over a few circumstances that are likely to give rise to the common interest privilege. Some of these scenarios are especially relevant to our audience, like cases involving product defects and insurance disputes. Additionally, this essay will discuss some practice guidelines that attorneys may find useful in preserving the common interest privilege and preventing its possible waiver.

What is Common Interest Privilege?

The common interest privilege extends attorney-client confidentiality. Stated differently, there is some overlap between the common interest and attorney-client privileges. Instead, the common interest privilege fundamentally builds upon attorney-client secrecy. Let’s review it.

Attorney-Client Privilege

Confidential communications between lawyers and clients, intended for providing or receiving legal advice, are generally protected from court discovery. The attorney-client privilege, a highly regarded legal privilege, is strictly enforced by courts in cases involving discovery issues.

The attorney-client privilege is fundamentally protected by law, and courts often grant this privilege. If the information is shared with someone other than the client, attorney, or third party, the privilege may be violated.

Privileged emails between lawyers and clients are frequently forfeited if one party forwards the correspondence to a third party. Waiver means that the email is open to adversarial discovery and may be admitted as evidence in court. Depending on how significant the communication in question was, a case could suffer greatly from such a waiver.

The law has made numerous exceptions to the general rule that sharing an otherwise privileged communication can destroy the privilege because it is frequently necessary for attorneys to include non-legal parties as members of their “team” to give their clients the best and most comprehensive representation possible. For example, many jurisdictions refuse to find that communicating or sharing documents with a third party results in waiver when that third party is required to convey legal advice (e.g., an accountant assisting in the translation of complex financial information for the client’s benefit, or a Russian translator communicating with a non-English speaking client). Furthermore, correspondence between an entity, its lawyer, and its “functional” employee in the case of a third-party contractor serving as the “functional equivalent” of an employee usually stays confidential.

Co-client and Joint Defense/Plaintiff Privileges

The “co-client” or “joint client” privilege, which expands the attorney-client privilege to cover additional parties without the danger of waiver, is more significant for this article because it has been recognized by courts. Multiple clients hiring the same attorney(s) can protect communications between them from discovery. This prevents the lawyer’s privilege from being perceived as a third party, potentially leading to its waiver and termination.

Expanding on the co-client privilege, the next extension of the privilege involved including additional attorneys in addition to clients. Under the “joint defense” privilege, two groups of clients and their separate counsel can communicate with one another without the plaintiff, who serves as their shared opponent, learning of it. The joint defense version of the attorney-client privilege covers defendants in similar but different cases as well as in the same case while the matter is still pending.

Although both the co-client and joint defense versions of privilege currently apply in civil litigation, the joint defense version of the attorney-client privilege appears to have originated in criminal law, similar to the co-client version.

Courts recognize this privilege as a joint plaintiff, applicable when plaintiffs are pursuing similar litigation in the same/separate courts.

Common Interest Privilege

The main point of this article can be found by expanding on the joint defense privilege’s logic to include the common interest privilege, which permits confidential communication between two groups of clients and their separate counsel without the need for ongoing litigation (at least in most courts). The supposedly privileged conversations may take place long before any such lawsuit is expected or even begins, but the legitimacy of a statement of a common interest privilege may not be evaluated until after litigation occurs.

Terminology Varies across Jurisdictions

Attorneys may discover that different jurisdictions use different terminology when discussing the co-client, joint defense/plaintiff, and common interest privileges. Certain judges may use informal phrases without making a clear distinction between them. The courts are addressing the finer points of recent case law extensions of attorney-client privilege.

Whatever nomenclature a particular court chooses, it appears that all jurisdictions acknowledge each of these expansions of the attorney-client privilege. Practitioners should use language preferred by the relevant jurisdiction, considering that other courts may have a different or inconsistent lexicon.

What Counts as a Sufficient “Common” Interest?

Common interest privilege is a legal principle that allows attorneys to protect their client’s interests in a dispute. It is often invoked in situations where the parties involved have opposing interests. The definition of “common” varies, with some cases suggesting that a shared interest equates to an identical interest. Some argue that something other than similar interests could activate the privilege. In instances other than mergers and acquisitions (M&A), like the Florida Visual Scene case, the common interest privilege is being put to the test.

The defendant processor makes an effort to stop a defendant manufacturer from sharing certain of its communications with the plaintiff. The trial court ruled that discovery was appropriate, but the appeals court overturned the trial court’s decision, concluding that communications were shielded from discovery. The court acknowledged that parties may have a shared legal interest in one or more matters but not in other matters.

Both the plaintiff manufacturer and the defendant processor may raise the common interest privilege in an alternative responsibility argument. Overlapping coalitions can arise in litigation involving more than two parties, each of which would be shielded by a joint defense or common interest privilege, even though the members of each privileged group would otherwise be adversaries.

Who Can and Cannot Have Direct Communication?

The common interest privilege is only applicable in cases where every distinct client group has a different legal team. Common interest privilege cannot exist if a group of clients and their attorneys speak with an unrepresented party. The person not represented is a third party who nullifies the privilege and establishes a waiver.

Courts generally believe that the common interest privilege is only applicable in instances where attorneys’ communications are protected. The privilege may be void if clients or lawyers representing one client group communicate directly with another client group. Nonetheless, at least one case has shown that conversations between a lawyer from one client group and a client represented by a different lawyer who isn’t a party to the communication can be covered by the common interest privilege.

“Common Interest” Privilege Tightened Up in New York

In 2016, New York’s highest court reversed a 2014 decision that expanded the application of the common interest doctrine to commercial transactions, such as mergers, where litigation was neither pending nor anticipated. In Ambac Assurance Corporation v. Countrywide Home Loans. The court clarified that this approach is applicable only to separate parties’ exchanges in ongoing or anticipated litigation cases. Communication discovery is common as a result of the exchange of “privileged” communications in cross-jurisdictional transactions, like merger agreements.

Considerations for Practical Application

A joint agreement between client groups and their attorneys can increase the chances of a court upholding a claim of the common interest privilege. In close cases, a common interest agreement can favor judges by demonstrating a common legal interest protected by privilege. Lawyers in a common interest group should manage conversations, while attorneys handle privileged communications. Practitioners should research secondary authorities, case law, and precedents to avoid potential waivers.


What is California’s common interest privilege?

September 2022. 87 pages. Comprehending the doctrine of common interest. When two lawyers represent clients who have similar legal interests, their discussions are protected by the common-interest concept. This case does not fall under the conventional rule that sharing private information with third parties often waives such privilege.

What is Privilege Interest?

Common law’s public interest privilege prohibits the forced release of records or information that is not in the public interest.

What does a banking privilege mean?

A bank’s privileged banking program is intended for its wealthiest customers.

What is the privilege principle?

The principle of least privilege (PoLP) is an information security concept that dictates that only those with the necessary data, resources, and programs should access them.


Jurists often misinterpret common interest attorney-client privilege with related doctrines, leading to confusion for lawyers and courts. A lawyer can enhance the privilege and prevent harmful court papers by focusing on key privilege components, carefully examining relevant case law, and implementing the article’s advice.

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