Legal Definitions - common-interest doctrine

The common-interest doctrine is a legal principle that allows parties with a shared legal interest to exchange privileged information, such as communications with their lawyers, without losing the protection of the attorney-client privilege. This doctrine applies even when these parties are represented by separate attorneys, as long as they are cooperating on a common legal strategy to achieve a shared objective.

Its purpose is to facilitate collaboration among parties who have aligned legal interests, enabling them to mount a more effective defense or pursue a common claim without fear that their shared confidential information will later be discoverable by an opposing party.

• Example 1: Multiple Defendants in a Product Liability Lawsuit

  Imagine three different pharmaceutical companies are sued by a group of plaintiffs alleging that a common ingredient used in their respective medications caused adverse health effects. Each company has its own legal team, but they all face similar claims regarding the same ingredient.

  Under the common-interest doctrine, these companies might agree to share legal strategies, research findings, and internal analyses related to the common ingredient. This shared information, which would normally be protected by each company's attorney-client privilege, remains privileged even when exchanged among them. The doctrine protects these communications from being discovered by the plaintiffs, as the companies have a shared legal interest in defending against similar claims regarding the ingredient.

• Example 2: Companies Involved in a Merger or Acquisition

  Consider a situation where Company A is acquiring Company B. During the extensive due diligence phase, Company B's legal team shares confidential legal advice with Company A's legal team regarding potential environmental liabilities associated with Company B's properties, or ongoing litigation risks.

  Both companies have a common legal interest in successfully completing the acquisition while understanding and mitigating legal risks. The common-interest doctrine ensures that this exchange of sensitive legal information, which would normally be protected by attorney-client privilege for Company B, remains privileged. This prevents a third party (e.g., a regulatory agency, a competitor, or a future litigant) from accessing these communications and using them against either company.

• Example 3: Businesses Facing a Government Investigation

  Suppose several financial institutions are under investigation by a government agency for alleged market manipulation involving a specific type of trading activity. Each institution retains its own legal counsel to represent its individual interests.

  However, because they are all facing a similar investigation from the same government body, they may agree to form a common-interest group. Within this group, they can share information about the government's requests, their internal investigation findings, and potential defense strategies. The common-interest doctrine protects these shared communications, allowing them to coordinate their responses and legal positions without waiving their individual attorney-client privileges, as they all share a common legal interest in responding to and defending against the government's investigation.