The Federal Bureau of Internal Security (FBIS) is the internal security and counterintelligence unit of the Federal Confederation, operating under the jurisdiction of the Federal Sheriff. It is responsible for monitoring internal threats, preventing sabotage, and stabilizing society by handling cases that fall outside conventional law enforcement. While the Federal Sheriff and Local Sheriffs focus on enforcing public law, the FBIS specializes in matters of national security, including black market activity, espionage, and political destabilization attempts.

Unlike intelligence agencies of the past, the FBIS is not a large-scale secret service but a small, specialized unit with about 25 active agents—some full-time, others called upon as needed. Agents are selected through GAIA’s job assignment process in accordance with the principles of Communardism, ensuring that those best suited for intelligence work are assigned to the Bureau.

While the FBIS does not operate independently, it reports directly to the Federal Sheriff and works closely with the Federal Council on cases that affect the stability of the Confederation.

The FBIS was formally established in 2634, during the second term of Federal Sheriff Evander Rosenberg, following increased concerns about rising political tensions, black market activity, and potential sabotage by Individualist factions in Firetown. The agency was designed as a preventive measure to monitor internal threats, particularly those that could undermine the Peace Treaty and the Federal Confederation’s governance.

After the assassination of Federal Sheriff Evander Rosenberg in 2635, the FBIS gained expanded authority under Mandla Friedberg's administration, taking a more aggressive stance on political dissent and counterintelligence operations.

The Federal Bureau of Internal Security (FBIS) operates under the nominal authority of the Federal Sheriff, but in practice, it maintains direct communication with the Federal Council and operates largely independently. The Federal Sheriff’s role is to enforce laws, while the FBIS ensures internal stability—a distinction that has led to tensions between the two institutions.

The FBIS can override the authority of Local Sheriffs if a case is classified as a matter of national security. However, due to concerns over overreach and potential abuses, all operations classified as “extreme interventions” must receive authorization from the Federal Council.