 Two years after overturning Roe v. Wade, the U.S. Supreme Court undid another major legal precedent this week. The Chevron Doctrine isn't as well known, but its reach into the workings of government and the lives of everyday Americans is massive. Thousands of rules and regulations set by federal agencies like the FDA and EPA could now be endangered. Andrew Mergen spent 30 years as an attorney at the Department of Justice Environment and Natural Resources Division.