The bill introduces Chapter 507-I, titled "Anti-SLAPP Substantive Immunity," which aims to protect individuals and organizations from strategic lawsuits against public participation (anti-SLAPP). It establishes qualified immunity for defendants in legal actions that infringe upon their First Amendment rights, allowing them to file a special motion to dismiss if claims are based on their exercise of free speech or petition rights concerning public issues. The bill outlines the process for invoking this immunity, requiring plaintiffs to demonstrate a probability of prevailing on their claims to overcome it. Additionally, it specifies that this immunity applies to various legal processes and allows defendants to recover costs and attorney fees if they successfully invoke it. However, government entities and employees acting in their official capacity cannot claim this immunity, although it can be used against them.

Furthermore, HB 391-FN strengthens protections against SLAPP by introducing new legal provisions and modifying existing ones. It mandates that any motion for discovery must be specific, and if it lacks specificity, it will be denied, allowing the non-moving party to recover reasonable attorneys' fees. If a special motion to dismiss is granted, it will be treated as an adjudication on the merits. The bill also allows parties to invoke anti-SLAPP protections through a separate action or counterclaim, enabling recovery of costs and fees if their motion is meritorious. Additionally, it establishes a cause of action for New Hampshire citizens sued in other jurisdictions that refuse to apply the state's anti-SLAPP protections, allowing them to seek statutory damages and recover costs associated with both the foreign and New Hampshire actions. The provisions will apply retroactively to all pending actions in New Hampshire and, where permissible, to actions in federal courts and foreign jurisdictions, with the act set to take effect on January 1, 2026.