Miller & Chevalier hosted a webinar to navigate issues arising from the recent Supreme Court ruling in Mayo Foundation for Medical Education & Research v. United States, which introduced a new standard of judicial deference for tax regulations issued by the US Department of the Treasury. The decision will change the way in which taxpayers need to approach challenges to tax regulations, and can be expected to cause the agencies to take a more aggressive approach in the regulatory and administrative guidance process. With the two-step Chevron deference analysis now the clear standard for tax regulations, tax practitioners need to understand the ways in which that standard will apply to tax regulations in order to successfully craft arguments at the administrative level and in court where a tax regulation is at issue. At the same time, practitioners should understand the limits of Mayo and the constraints that remain in place on the IRS's ability to use the regulatory guidance process as a weapon in litigation.