Larry Gibbs comments on the U.S. Supreme Court's ruling in Mayo Foundation for Medical Education and Research v. United States, which held that IRS regulations should be granted a high level of judicial deference, giving the agency more rulemaking power and makes it harder to challenge tax regulations in court. Gibbs, a former Commissioner of Internal Revenue, said that the ruling "puts a pretty heavy burden on those who are now going to argue that regulations are invalid. The Chevron standard is a pretty difficult standard." While it will not be impossible to make those arguments, it will be "very, very difficult after Mayo," Gibbs said.