Which department is responsible for prescribing standards and guidelines pertaining to federal information systems under FISMA?

The Department of Homeland Security (DHS) is tasked with prescribing standards and guidelines concerning federal information systems under the Federal Information Security Management Act (FISMA). This responsibility falls within the DHS's broader mission to protect and secure the nation’s critical information infrastructure.

FISMA establishes a comprehensive framework for ensuring the effectiveness of information security controls over information resources that support federal operations and assets. Under this act, the DHS plays a crucial role in the implementation of security policies and procedures, aiming to enhance the protection of federal information systems.

The other departments listed, while having various roles in federal security and information management, do not have the primary authority under FISMA for setting these standards and guidelines. The Department of Defense, Department of Justice, and Department of Treasury each manage their own respective areas of expertise in relation to national security and information management, but it is the DHS that specifically focuses on the overarching standards for federal information systems as outlined in FISMA.