Trumbull was a leading abolitionist attorney and key political ally to Abraham Lincoln and authored several landmark pieces of reform as chair of the Judiciary Committee during the American Civil War and Reconstruction era, including the Confiscation Acts, which created the legal basis for the Emancipation Proclamation; the Thirteenth Amendment to the United States Constitution, which abolished chattel slavery; and the Civil Rights Act of 1866, which led to the Fourteenth Amendment to the United States Constitution.

[2] While living in Belleville in November 1837, Trumbull became aware of the murder of Elijah P. Lovejoy, an abolitionist minister and newspaper publisher, in nearby Alton.

In a letter to his father, the young Trumbull predicted, "[Lovejoy's] death and the manner in which he was slain will make thousands of abolitionists, and far more than his writings would have made had he published his paper an hundred years.

[2] Trumbull remained Secretary of State for two years, devoting most of his time to his legal practice while his brother Benjamin cared for the routine duties of the office.

In 1842, the Bank had suspended payments after the value of its notes had fallen to fifty cents on the dollar, and Trumbull considered repeated efforts to legalize the suspension futile and disgraceful.

His resignation divided the Illinois Democratic Party, with the Trumbull faction including Virgil Hickox, Samuel H. Treat, Ebenezer Peck, and Mason Brayman.

Trumbull then returned to Belleville to practice law and marry Julia Jayne, a physician's daughter and a friend of Mary Todd Lincoln.

[4] Following the passage of the Kansas–Nebraska Act in 1854, Trumbull, Gustav Koerner (now Lieutenant Governor), and other anti-slavery Democrats began organizing an anti-Nebraska ticket in the 8th congressional district.

In a speech on October 16, 1854, Lincoln delivered a moral, legal, economic, and historical case against slavery which won him the endorsement of many anti-slavery members of the upcoming Illinois legislature, including Owen Lovejoy and John A.

In it, he criticized the majority report of the Committee on Territories, submitted by his Illinois colleague Stephen A. Douglas, which defended the actions of "border ruffians" against claims of electoral fraud.

The speech sparked a debate between the two, in which Douglas said Trumbull's claim to be a member of the Democratic Party was a "libel" and that his junior colleague had been elected by "Black Republicans," "Know-Nothings," and "Abolitionists."

His speeches won praise from his colleagues Charles Sumner and Salmon P. Chase and served to dispel doubts from anti-slavery Lincoln men in Illinois.

After the convention, Lincoln and Trumbull turned their focus to electing a Republican ticket in Illinois, and they were successful despite Frémont's failure to carry the state.

In the fall, Lincoln carried the state of Illinois against Douglas and won the presidency against a divided opposition, while Trumbull ensured his own re-election to the Senate by a single legislative seat.

Following their successes, Lincoln wrote to Trumbull, advising him to resist calls to compromise with the South on the extension of slavery in order to stave off growing threats of secession.

[9] As a top Lincoln ally, Trumbull fielded many calls from office seekers after the election, hoping to win his favor and an appointment from the new president.

This Act to permit the seizure of contraband used in rebellion was drafted by Trumbull to include persons held in slavery employed in military or naval work against the Union war effort.

As drafted by Trumbull, the initial bill provided that all property held by rebels was immediately forfeited to the United States but preserved the rights of Southern citizens who claimed loyalty to the Union.

[13] As the war effort stalled in January and February 1864, Trumbull became estranged from Lincoln politically and began to privately predict the President would fail to be reëlected or even nominated by the Republican Party.

In January 1864, Senator John B. Henderson of Missouri, himself a slave holder, proposed a resolution amending the Constitution to include, "Slavery or involuntary servitude, except as a punishment for crime, shall not exist in the United States."

Neither slavery nor involuntary servitude, except as punishment for crime whereof the party shall have been duly convicted, shall exist within the United States or any place subject to their jurisdiction.

Trumbull spoke at length in its favor, arguing there could be no doubt that the Civil War originated in the institution of slavery and the hostilities between its proponents and opponents.

However, Trumbull did join the radical Republicans in arguing that under an expansive reading of the Thirteenth Amendment, Congress could bar laws and practices, including sharecropping or racial discrimination, which amounted to or threatened the reintroduction of slavery.

Trumbull's bill proposed citizenship be extended to all persons of African descent born in the United States and banned discrimination on account of race, color, or previous condition of slavery.

In a response to Johnson's veto, Trumbull concluded by saying, "If the bill now before us... cannot be passed, then the constitutional amendment proclaiming freedom to all the inhabitants of the land is a cheat and a delusion."

Blinded by partisan zeal, with such an example before them, they will not scruple to remove out of the way any obstacle to the accomplishment of their purposes, and what then becomes of the checks and balances of the Constitution, so carefully devised and so vital to its perpetuity?

[23] All seven senators, resisting the pressure imposed on them, broke party ranks and defied public opinion, voting for acquittal, although they knew their decision would be unpopular.

After the trial, Congressman Benjamin Butler of Massachusetts conducted hearings in the House on widespread reports that Republican senators had been bribed to vote for Johnson's acquittal.

Butler's hearings and subsequent inquiries revealed evidence that some acquittal votes were acquired by promises of patronage jobs and cash cards.

Trumbull was part of the three-member legal team, which included Clarence Darrow, when their habeas corpus case In re Debs was heard by the US Supreme Court in 1895.