On January 20, 2021 newly inaugurated President Biden issued an executive order directing Federal agencies to review environmental regulations and policies promulgated by the previous administration – specifically adopted or issued between January 20, 2017 and January 20, 2021. The order emphasizes that when reviewing and developing new regulations agencies should be guided by the best science available and aim to improve public health and protect the environment. The order directs agency heads to consider developing and proposing new regulations, guidance documents, and other orders consistent with this policy. This executive order is expected to impact more than 120 actions conducted by the Trump administration relating to the environment and energy undertaken by various agencies. The executive order sets specific deadlines for agencies to rescind or revise for a number of rules including the following: “Oil and Natural Gas Sector: Emission Standards for New, Reconstructed, and Modified Sources Reconsideration,” 85 Fed. Reg. 57398 (September 15, 2020) by September 2021; “National Emission Standards for Hazardous Air Pollutants: Coal- and Oil-Fired Electric Utility Steam Generating Units—Reconsideration of Supplemental Finding and Residual Risk and Technology Review,” 85 Fed. Reg. 31286 (May 22, 2020) by August 2021; and “Strengthening Transparency in Pivotal Science Underlying Significant Regulatory Actions and Influential Scientific Information,” 86 Fed. Reg. 469 (January 6, 2021) as soon as possible.