The Maryland State Capitol, in the snowy background (AP Photo/Susan Walsh)

A century and a half after the end of the Civil War, Maryland legislators will attempt to rescind the state’s ratification of a proposed constitutional amendment that would have prohibited Congress from abolishing slavery.

The proposed amendment, known as the “shadow” 13th Amendment, was part of an effort to compromise with slave states to avert the war. The 36th Congress passed the measure just days before it adjourned, after seven Southern states had seceded from the Union and less than a week before President Abraham Lincoln was inaugurated.

“No amendment shall be made to the Constitution which will authorize or give to Congress the power to abolish or interfere, within any State, with the domestic institutions thereof, including that of persons held to labor or service by the laws of said State,” read the proposal, first sponsored by Rep. Thomas Corwin of Ohio and Sen. William Seward of New York, both Republicans.

The Confederacy, which was busy seceding, ignored the proposed language. But two states, Ohio and Maryland, ratified the amendment, even after the Civil War had begun. Maryland’s General Assembly ratified the bill on Jan. 10, 1862. Ohio’s legislature rescinded their ratification in 1864, but Maryland never rescinded it.

Now, lawmakers want to take back their ratification.

“It’s a relic, but it’s a blot on our history,” state Sen. Brian Frosh (D) told the Baltimore Sun this week. Frosh proposed rescinding ratification after hearing from a 21-year old student from his district.

A state Senate committee will take up the proposal to rescind ratification in a hearing Thursday.

Three years after the Corwin Amendment went to the states, the Senate passed what became the actual 13th Amendment, which banned slavery and involuntary servitude. The House adopted the language in January 1865, and by the requisite number of states on Dec. 6, 1865.

Maryland, a slave state that nonetheless stuck with the Union during the Civil War, abolished slavery in its 1864 Constitution. Thereafter, the state was known as the “Free State.” More than half a century later, the editor of the Baltimore Sun mockingly suggested applying the “Free State” label to the state’s unwillingness to go along with prohibition.