Jenner & Block is an American law firm with offices in Chicago, London, Los Angeles, New York City, San Francisco, and Washington, D.C. The firm is active in corporate litigation, business transactions, the public sector, and other legal fields. It has litigated several prominent cases before the United States Supreme Court. As of 2014, it was the 103rd-largest law firm in the US, based on The American Lawyer's annual ranking of firms by headcount.