Belva Lockwood, a graduate in 1873 of the the the National University Law School (now GW Law), became the first woman to argue a case before the Supreme Court. Once she had completed her course work, the law school refused to grant her a diploma, without which she could not practice law. She petitioned President U.S. Grant, in his role as president ex officio of the law school, to issue her diploma; she received it one week later.
Lockwood set up her practice in the District and, although Lockwood was admitted to the District of Columbia bar, some judges refused to allow her to appear in their courtrooms because she was a married woman. She was also denied membership in the Maryland bar. She petitioned Congress to pass an anti-discrimination law that would permit a woman to appear in any court in the District, including the Supreme Court. The law was passed in 1879; Lockwood was admitted to the Supreme Court bar later that year.
Lockwood first ran for President in 1884 and again in 1888 on the National Equal Rights Party ticket. She received several thousand votes, unusual since women did not have the right to vote.
For the remainder of her life, Lockwood fought for equal rights for both women and minorities. She died in 1917, just a few years before universal suffrage became reality with the 19th Amendment.
Read more about Lockwood:
Jill Norgren, Belva Lockwood: The Woman Who Would be President
Mary Virginia Fox, Lady for the Defense: A Biography of Belva Lockwood
Marian Calabro, Great Courtroom Lawyers: Fighting the Cases that Made History