In October 1910, President
William Howard Taft announced he would appoint Lewis as a
United States Assistant Attorney General, sparking a national debate. A North Carolina newspaper wrote that the "Lucky Colored Man" would hold the "Highest Public Office Ever Held by One of His Race." The appointment was reported to be "the highest office in an executive branch of the government ever held by a member of that race."
The Boston Journal wrote that Lewis had received "the highest honor of the kind ever paid to a negro," such that he then ranked in "a position of credit and influence second only to that occupied by
Booker T. Washington." president of
Tuskegee Institute.
The Washington Evening Star concluded that the appointment of Lewis to "a higher governmental position than any heretofore given to a colored man" would result in a confirmation battle with southern Democrats, who had imposed racial segregation across the South. An Illinois paper mistakenly reported in December 1910 that opposition to Lewis was so strong that Taft had decided not to place his appointment before the Senate. However, Taft did not withdraw the nomination, and a Georgia newspaper predicted a "Hard Fight Is Coming" on the nomination: After a two-month fight against him waged by the Southern Democratic block (Southern states had disenfranchised most blacks at the turn of the century, and white Democrats dominated southern politics in a one-party system), the Senate confirmed Lewis as an Assistant Attorney General in June 1911. After being sworn into office, Lewis went to the White House, where he personally thanked President Taft for the high honor. Lewis's initial assignment was to defend the federal government against all Indian land claims. Lewis was the highest-ranking of four African Americans appointed to office by Taft, who were known as his "Black Cabinet:"
Henry Lincoln Johnson as Recorder of Deeds for the District of Columbia,
James Carroll Napier as Register of the Treasury, and
Robert Heberton Terrell as District of Columbia Municipal Judge.
Challenge from southern ABA members sent a "spirited letter" to all 4,700 members of the ABA after the ouster of Lewis In 1911, Lewis was among the first African Americans to be admitted to the
American Bar Association (ABA). In September 1911, Lewis faced a campaign for his ouster from the ABA. Though there was no racial restriction in the organization's charter, some members threatened to resign if Lewis stayed. When Lewis's name had been submitted with others by the Massachusetts Bar Association, his race had not been disclosed. The Southern white delegates said they did not know Lewis was a
negro until he entered the convention hall. Lewis refused to resign. When the ABA's executive committee voted to oust Lewis in early 1912, U.S. Attorney General
George W. Wickersham sent a "spirited letter" to each of the 4,700 members of the ABA condemning the decision. While northern newspapers congratulated Lewis and Wickersham for their stance, a
Charlotte, North Carolina newspaper criticized Lewis for his lack of "good manners" in refusing to resign: The insistence of William H. Lewis of Boston, now an Assistant Attorney General, that he retain his membership in the American Bar Association notwithstanding objections is due condemnation upon other grounds than those of race. He would probably not have been elected if it had been known by the majority of delegate who he was. Having thus slipped into an organization, he should offer his resignation pending a real decision of the matter. This is simply what any one elected to any manner of organization through any sort of ignorance or misapprehension is required by good manners to do. Lewis became an advocate for African Americans in the legal profession. During the fight over his removal from the ABA, Lewis published an article saying that many white men "know intimately only the depraved, ignorant, vicious negros – those who helped to keep the dockets filled." In August, 1912, the ABA as a body voted to overrule the executive order and restore Lewis and two other ousted Black lawyers to membership. The measure that passed also required that future Black applicants must identify their race. ==Private law practice==