49 U.S.C. § 20104 — Emergency authority

(a) Ordering Restrictions and Prohibitions.
(1) If testing, inspection, investigation, or research carried out under this chapter shows the Secretary of Transportation that an unsafe condition or practice — or a combination of them — is causing an emergency involving a risk of death, personal injury, or significant environmental harm, the Secretary can immediately order whatever restrictions or bans are needed to fix it, without following the hearing requirement in section 20103(e).
(2) The order must describe the condition or practice causing the emergency and set out how someone can ask for relief from the order. This doesn't limit how long the Secretary can keep the order in effect while the emergency situation continues.

(b) Review of Orders. After issuing the order, the Secretary must provide an opportunity to have it reviewed under section 554 of title 5. If someone files for review and it isn't completed within the 30-day period after the order was issued, the order stops being effective at the end of that period — unless the Secretary decides in writing that the emergency situation still exists.

(c) Civil Actions To Compel Issuance of Orders. A railroad employee (working in interstate or foreign commerce) who could face imminent physical injury on the job because the Secretary — without any reasonable basis — failed to issue an emergency order, or that employee's authorized representative, can sue the Secretary in a federal district court to compel the order. The suit must be filed where the emergency is alleged to exist, where the employing railroad has its main office, or in the District of Columbia. Courts can review the Secretary's failure to act only under section 706 of title 5.