[6] After teaching, he traveled to Kentucky and heard the famous politician Henry Clay speak, then returned to Concord to study law at his father's office.

[11][13] In July 1870, Hoar became the first attorney general to head the Department of Justice, created to strengthen the enforcement and investigation powers of the President.

One of Hoar's first duties as Attorney General was to rule on the appointment of New York businessman Alexander T. Stewart as Secretary of the Treasury.

Stewart was opposed by Senators Charles Sumner and Roscoe Conkling, who cited a 1789 law prohibiting any Secretary who was "concerned or interested in carrying on the business of trade or commerce.

[17] On December 14, 1869,[18] President Grant nominated Hoar to the associate justice seat on the United States Supreme Court created by the Judiciary Act of 1869.

As Attorney General, Hoar had alienated senators by not consulting them before recommending to the president nominees for circuit judge.

In addition, senators were indignant about Hoar's positions on patronage reform and about his previous opposition to the impeachment of Andrew Johnson.

[21] On Hoar's advice, Grant nominated William Strong and Joseph P. Bradley to fill the twin vacancies.

[21] President Grant, Hoar, and his entire cabinet had been against the Court's 4–3 Hepburn ruling, believing that the nation's money supply would be reduced and that this would ruin the economy.

[22] On March 31, 1870, Hoar went before the Supreme Court and argued that the Hepburn decision caused instability in the national economy, in case the country needed to print money during an emergency, as had been done during the American Civil War.

[23] One year later, with justices Strong and Bradley on the bench, the Court reversed the Hepburn ruling in a 5–4 decision, making paper money legal tender.

[23] Although President Grant and Hoar were accused of packing the Court, Strong and Smith's names had been submitted to the Senate prior to the Hepburn decision.

[23][24] Hoar was a moderate Republican who opposed federal intervention in protecting African American citizens during Reconstruction.

[25] President Grant, however, had lost faith in the Southerners to comply with constitutional and federal law that protected African Americans.

In order to increase the federal government's investigative and enforcement powers, Congress created the Department of Justice and Solicitor General in June 1870.

[27] President Grant was under increased pressure to replace Hoar with a more Radical Attorney General, one who did not oppose federal intervention to stop lawlessness in the South.

Controversy ensued when Grant's personal secretaries allowed Hoar's resignation letter to be disclosed to the press.

Akerman was from Georgia and aggressively supported Reconstruction and the federal protection of African American civil rights.

A subsequent joint arbitration commission, acting under the treaty, issued a decision in September 1872, rejecting American claims for indirect war damages but ordering Britain to pay the United States $15.5 million (~$352 million in 2023) as compensation for the Alabama claims.