Legal preparedness is commonly assessed through the laws, policies and institutional capacities in place before an emergency. This article examines one component of that capacity: delegated authority to make binding rules. It combines a deduplicated corpus of 52,887 United Kingdom statutory instruments issued between 1987 and 2022 with the Hansard Society census of 582 coronavirusrelated instruments. A monthly negative-binomial interrupted series estimates an immediate increase in the rate of health instruments after March 2020 (incidence-rate ratio 4.99, 95% CI [3.42, 7.29]). Among health instruments with observable dates, the median interval between making and entry into force fell from 33 days in 2015–2019 to 2 days in 2020. Coronavirus rulemaking drew on 140 enabling Acts across several policy sectors. Most instruments did not require parliamentary approval before they were made, and 54.7% of made-negative instruments breached the 21-day convention. These findings distinguish the availability of delegated authority from the speed and reach of its activation and from the opportunity for parliamentary review. They document regulatory acceleration and limited opportunities for prior scrutiny, but do not establish whether subsequent parliamentary activity changed the law.