After going to Harvard Law School and continuing to play football, Lewis was the first African American in the sport to be selected as an All-American.

When Lewis was appointed as an Assistant Attorney General in 1910 by President William Howard Taft, it was reported to be "the highest office in an executive branch of the government ever held by a member of that race.

[4] With the assistance of Virginia Normal's first president, John Mercer Langston,[4] Lewis transferred to Amherst College in Massachusetts.

Du Bois, a professor at Atlanta University and later founder of the NAACP, went to the Amherst commencement ceremony to see Lewis and George W. Forbes, another African-American student, receive their diplomas.

An article published by the College Football Hall of Fame noted that, while Lewis "was relatively light for the position (175 pounds) he played with intelligence, quickness and maturity.

[4] The Boston Journal wrote that Lewis was owed "much of the credit for the great defensive strength Harvard elevens have always shown.

[4][11] Upon the book's release, one reviewer noted: A new feature, hitherto inadequately treated by previous authors, is the exhaustive treatment of fundamentals or the rudiments of the game, such as passing, catching, dropping upon the ball, kicking, blocking, making holes, breaking through and tackling.

[12]In a 1904 article, The Philadelphia Inquirer placed Lewis on par with the legendary Walter Camp in his knowledge of the game, writing, "The one man whom Harvard has to match Mr. Camp in football experience and general knowledge is William H. Lewis the famous Harvard centre of the early nineties and the man who is the recognized authority on defense in football the country over.

While opposing unnecessary roughness, Lewis argued against proposed changes, noting that he did not want to watch "a game of ping-pong or marbles upon the football field.

The author noted that Lewis "owes his appointment to the fact that he is an uncommonly good football coach and that President Roosevelt is a Harvard man.

According to the story, Harvard men were "unwilling to lose Lewis's services in the football season, and they undertook to make his residence here so profitable that he would remain.

"[26] 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.

"[28][29][30] 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.

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.

[32] 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.

Whether or not Lewis would ever avail himself of these privileges, a number of southern Democrats feel that they do not want to be a party to elevating him to an eminence where such recognition would be his as a matter of official right.

[37] 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.

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.

"[46] He called for blacks to train and form "an army of negro lawyers of strong hearts, cool heads, and sane judgment" to help the large number of African Americans who were "exploited, swindled and misused.

He developed a reputation as an outstanding trial lawyer and appeared before the United States Supreme Court on more than a dozen occasions.

After a white barber in Cambridge refused to shave Lewis, he filed a suit seeking $5,000 in damages and successfully lobbied for the passage of a Massachusetts law prohibiting racial discrimination in places of public accommodation.

[53]While serving as Assistant Attorney General, Lewis learned that a young African-American graduate of Harvard had been refused employment at a prominent Boston trust company on account of race.

"[54] Lewis was one of three persons invited to deliver an address at Boston's Symphony Hall memorial to abolitionist Julia Ward Howe following her death in 1910.

[57] In the summer of 1919, after Lewis's speech, the economic and social tensions of the postwar years erupted in numerous white racial attacks against blacks in northern and midwestern cities where blacks had migrated by the thousands and were competing with recent European immigrants; it was called Red Summer.

Lewis married Elizabeth B. Baker, who had been a student at Wellesley College, and the couple lived on Upland Road in Cambridge, where they raised three children.