The CERTAIN Act aims to significantly expedite federal permitting and environmental reviews for infrastructure projects by establishing clear timelines and accountability measures. It restricts federal agencies from revoking or altering existing authorizations unless specific conditions are met, such as a court order, prevention of immediate harm, or a material breach by the authorization holder, all requiring clear and convincing evidence and prior notice. These agency actions are subject to judicial review in the U.S. Court of Appeals, and agencies cannot seek vacatur or remand without the holder's consent. The bill mandates that agencies promptly acknowledge and review applications, determining completeness within 30 days and requesting specific additional information if needed. If an agency fails to act within set timelines, an application can be deemed complete , preventing indefinite delays. For projects requiring environmental review under the National Environmental Policy Act (NEPA), agencies must make timely determinations on the required level of review (e.g., environmental assessment or impact statement) and notify applicants. To prevent unnecessary delays, the Council on Environmental Quality (CEQ) is tasked with issuing guidance and mediating disputes between agencies and applicants regarding environmental reviews. If disputes remain unresolved, the CEQ Chair can provide specific direction on interagency coordination and process management. The legislation also establishes a lead agency framework for complex authorizations, requiring coordination with participating agencies to develop a coordination plan and a schedule with milestones for completing reviews. Crucially, the bill sets strict deadlines for environmental reviews and final agency actions, including a 30-day decision period for routine authorizations, which are deemed approved if the deadline is missed. For complex authorizations, final agency actions must be issued within 6 months for categorical exclusions, one year for environmental assessments, and two years for environmental impact statements. If agencies miss these deadlines or deviate from schedules, they must provide public notice, updated schedules, and an opportunity for administrative review. The Act also strengthens judicial review by treating agency failures to meet deadlines or actions to revoke authorizations as final agency actions , creating a rebuttable presumption of unreasonable delay. Courts are directed to issue decisions within 90 days and, if delay is found, to compel corrective action with specific deadlines. Finally, the bill addresses federal permitting capacity by requiring agencies to assess their personnel and, if insufficient, for the Office of Personnel Management to develop plans and authorize direct hire authority to ensure adequate staffing for timely reviews.