Bagenstos graduated from the University of North Carolina in 1990, and then received his J.D. in 1993 from Harvard Law School, magna cum laude. He received the Fay Diploma and was Articles Office Co-Chair for the Harvard Law Review. He clerked for Judge Stephen Reinhardt on the Ninth Circuit for one year, and then joined the Civil Rights Division of the U.S. Department of Justice. He served as Law Clerk to Justice Ruth Bader Ginsburg of the U.S. Supreme Court in the 1997/1998 Term. He has argued four U.S. Supreme Court cases, representing the plaintiff. In Fry v. Napoleon Community Schools, 137 S. Ct. 743, he won a victory for a girl with cerebral palsy who sought to bring her service dog with her to school; the Court reversed a lower-court decision throwing the case out of court. In Young v. United Parcel Service, 135 S. Ct 1338, the Court established new protections for pregnant workers. In United States v. Georgia, 546 U.S. 151, the Court upheld the constitutionality of Title II of the Americans with Disabilities Act, as applied in the case of a prisoner who used a wheelchair. And in Chevron v. Echazabal, 536 U.S. 73, the Court rejected the plaintiffs argument that he should be the one to decide if chemicals in the workplace posed too much risk to his health, given that he had hepatitis. In Mays v. Snyder, Bagenstos has been representing Flint residents seeking relief for injuries they received in the Flint Water Crisis; he litigated an appeal in which the 6th Circuit Court of Appeals held that Flint residents must receive the chance to make their constitutional case in court. In Husted v. A. Philip Randolph Institute, Bagenstos filed a challenging Ohio’s voter purge procedure, criticizing the Trump Administration’s reversal of longstanding U.S. Department of Justice policy on the National Voter Registration Act. Bagenstos has signed briefs in the U.S. Supreme Court in support of the antidiscrimination case brought by transgender student , and opposing a constitutional right to discriminate against same-sex couples by . He in favor of the Employment Non-Discrimination Act, which would protect workers against discrimination based on sexual orientation and gender identity. As Principal Deputy Assistant Attorney General, Bagenstos was second-in-charge of the Civil Rights Division, and supervised the Civil Rights Division's appellate work, disability rights enforcement, and other matters. In the disability rights area, he emphasized intensified enforcement of the Supreme Court's decision in Olmstead v. L.C., which requires that states provide services to people with disabilities in the most integrated setting appropriate to their individual situation. He also focused on ensuring that emerging technologies are accessible to people with disabilities. He has been a member of the faculty of Harvard Law School, and a visiting professor at UCLA School of Law and Michigan Law School. He was a professor of law from 2004 to 2009 at Washington University in St. Louis, and from 2007 to 2008, Associate Dean for Research and Faculty Development there. He is the author of Law and the Contradictions of the Disability Rights Movement,Samuel Bagenstos#cite note-3| and a Foundation Press casebook on Disability Law,Samuel Bagenstos#cite note-4| along with numerous articles. In 2018 he was an unsuccessful candidate for the Michigan Supreme Court.
