The Justice Department’s Antitrust Division has completed its review of Paramount’s proposed acquisition of Warner Bros. and concluded the transaction is not likely to substantially lessen competition. In most deal cycles, that would mark the end of the government review story. Here, it may be the beginning of the litigation story.

According to reports, attorneys general in California, New York, and potentially other states are preparing to challenge the merger anyway. That creates a familiar but still highly consequential dynamic in modern antitrust enforcement: federal clearance does not necessarily insulate a transaction from state-level attack.

Legally, the significance is straightforward. State AGs retain authority under federal and state antitrust laws to sue over mergers they believe threaten competition, even where the DOJ declines to act. For dealmakers, that means antitrust risk analysis can no longer stop with the federal agencies. Parties must evaluate whether politically active or industry-focused states may pursue their own theories of harm, seek a preliminary injunction, or force concessions that the DOJ did not demand.

For litigators, this is the kind of matter that can move quickly from regulatory review to emergency injunction practice. If a multistate complaint is filed, expect disputes over market definition, content licensing, advertising markets, streaming competition, bargaining leverage, and consumer impact. The forum selection and coalition structure will matter, as will whether the states proceed under Section 7 of the Clayton Act, parallel state statutes, or both.

In-house counsel and compliance teams should also pay close attention. A DOJ decision not to challenge may help with investor messaging, but it does not eliminate closing risk, integration uncertainty, or discovery exposure. Companies in regulated or politically visible industries should treat this as another reminder that merger planning now requires a dual-track strategy: agency advocacy on one side and state-enforcement contingency planning on the other.

The broader legal-industry takeaway is that antitrust federalism remains a live force in major transactions. Over the last several years, state AG offices have become increasingly willing to pursue independent enforcement agendas, especially where consumer pricing, media concentration, labor effects, or platform power are in play. A split between federal and state enforcers can complicate timing agreements, financing commitments, and board-level fiduciary analysis.

If the anticipated suit is filed, this matter could become a closely watched test of how far states are willing to press merger challenges after federal regulators stand down. For practitioners tracking antitrust litigation, the key question is no longer whether the deal cleared Washington, but whether it can survive the next courtroom.