
Taney was born in Maryland on St. Patrick's Day of 1777. He was the first Roman Catholic and the first non-Protestant every appointed to a presidential cabinet, as Attorney General, and as a member of the Court. He had been elected the Maryland State Senate in 1816 as a Democratic-Republican, serving until 1821. He served as a director of the Frederick County Bank from 1818 to 1823. When the 1824 presidential election splintered the Democratic-Republican Party, Taney became a staunch Jacksonian Democrat. Taney was appointed as Attorney General of Maryland in September 1827, and also served as chairman of the Jackson Central Committee of Maryland in the 1828 election. He served as state attorney general until 1831, when he resigned in order to serve in Andrew jackson's cabinet.
Taney first served as acting secretary of war and then as attorney general for Jackson. As attorney general, Taney wrote legal opinions which supported South Carolina's law prohibiting free African-Americans from entering the state, and another in which he gave the opinion that descendants of slaves could not become American citizens.
Taney supported Andrew Jackson in his opposition to rechartering the Second Bank of the United States. Likely because of this, Jackson gave Taney a recess appointment as secretary of the treasury in September 1833 during a congressional recess. Taney proceeded to withdraw federal funds from the Bank, effectively killing the institution. He established a system of government depositories. The following June, when Jackson officially nominated Taney as secretary of the treasury, the pro-bank majority in the Whig-dominated Senate voted 18–28 to deny Taney the job, making him the first Cabinet nominee in the nation's history to be rejected by the Senate.
Taney returned to Maryland and resumed his private legal practice. Jackson nominated Taney to fill a vacancy on the court in January 1835, notwithstanding the the Senate's rejection of Taney as Treasury Secretary. Taney was nominated to fill the post of retiring Associate Justice Gabriel Duvall. The Senate was scheduled to vote on Taney's confirmation on the closing day of the session that month, but the anti-Jackson Whigs who dominated the Senate blocked the vote and introduced a motion to abolish the open seat on the Court. The latter was unsuccessful, but the Whigs succeeded in preventing Taney's confirmation to the Court.
After the 1834 elections, Jacksonian Democrats regained control the Senate and, during the 1835 recess, Chief Justice John Marshall died. On December 28, 1835, Jackson sent the nomination of Taney as Chief Justice to the Senate, which had convened that month. Despite bitter opposition from Whig leaders Henry Clay, Daniel Webster, and Jackson's former Vice President John C. Calhoun, Taney was confirmed on March 15, 1836 by a 29–15 vote. He was sworn in as Chief Justice on March 28, 1836.
Taney's appointment marked a reversal in the direction of the court which, under Marshall, had supported a strong central government over states' rights. Taney and the other justices appointed by Jackson more often favored the power of the states. Uncharacteristically however it was the Taney Courtm which heart the case of slaves who had taken over the Spanish schooner Amistad, which upheld the right of the slaves, as free men to defend themselves by attacking the crew and trying to gain freedom. Taney joined Justice Joseph Story's unanimous majority opinion but left no written opinion of his own in the Amistad case.
In 1857 the Taney Court heard Dred Scott v. Sandford, a suit brought by a slave who had been kept in a free state for a period of time and claimed that he was now a freed man. The court overturned the Missouri Compromise and the decision is considered to have contributed to the outbreak of the Civil War. Five members of the Court were willing to dismiss the lawsuit by Dred Scott, on grounds based in Missouri law governing who could sue and be sued. But Taney wrote what came to be regarded as the opinion of the Court. His decision held that Congress had no authority to restrict the spread of slavery into federal territories, and that previous attempts to restrict slavery's spread, such as the 1820 Missouri Compromise, were unconstitutional. Of the eight associate justices at the time, James Moore Wayne, John Catron, Peter Vivian Daniel, Samuel Nelson, Robert Cooper Grier and John Archibald Campbell all agreed with Taney, while John McLean and Benjamin Robbins Curtis dissented. Curtis was so disgusted by the decision that he resigned from the court.
The Dred Scott v. Sandford decision was widely condemned at the time by opponents of slavery and was considered by many to be an illegitimate use of judicial power. It was considered to be the result of an illegitimate interference of the judicial branch of government by the political branch. President-elect James Buchanan wrote to Supreme Court Associate Justice John Catron, asking whether the case would be decided by the U.S. Supreme Court before his inauguration in March 1857. Buchanan hoped that a decision finding Scott to be a slave would quell unrest in the country over the slavery issue by issuing a ruling that put the future of slavery beyond the realm of political debate.
Buchanan successfully pressured Associate Justice Robert Cooper Grier, a Northerner, to join the Southern majority in the Dred Scott decision, to prevent the appearance that the decision was made along sectional lines. By present-day standards, such correspondence would be considered extremely unethical. Even under the more lenient standards of that century, Buchanan's applying such political pressure to a member of a sitting court should have been seen as improper. Republicans made an issue of Buchanan's influence on the decision by publicizing that Chief Justice Roger Taney had whispered in Buchanan's ear prior to Buchanan declaring, in his inaugural address, that the slavery question would "be speedily and finally settled" by the Supreme Court. Following the decision, Abraham Lincoln and other leaders in the Republican Party accused the Taney Court of carrying out the orders of the "slave power" and of conspiring with Buchanan to undo the Missouri Compromise.
The language used by Taney in the decision provides additional support for the contempt that this decision is held in by many. In his ruling, Taney said that African Americans, free or slave, had not been considered as part of the original community of people covered by the Constitution, but people of "an inferior order". It was his position that neither the Court nor Congress could now extend rights of citizenship to them. He wrote:
"It is difficult at this day to realize the state of public opinion in regard to that unfortunate race which prevailed in the civilized and enlightened portions of the world at the time of the Declaration of Independence, and when the Constitution of the United States was framed and adopted; but the public history of every European nation displays it in a manner too plain to be mistaken. They had for more than a century before been regarded as beings of an inferior order, and altogether unfit to associate with the white race, either in social or political relations, and so far unfit that they had no rights which the white man was bound to respect."
Taney's judicial views seem at odds with many of his own attitudes toward slavery. He emancipated his own slaves and even paid pensions to those who were too old to work. In 1819, he defended an abolitionist Methodist minister who had been indicted for inciting slave insurrections by denouncing slavery in a camp meeting. During the case, in his opening argument Taney called slavery "a blot on our national character." But by the time he wrote his Dred Scott opinion in 1857, he now called the opposition to slavery as "northern aggression", a popular phrase among pro-slavery Southerners. He hoped that a Supreme Court decision declaring federal restrictions on slavery in the territories unconstitutional would put the issue beyond the realm of political debate. Instead his decision inflamed Northern opposition to slavery and split the Democratic Party on sectional lines.
Taney administered the oath of office to President Abraham Lincoln on March 4, 1861. Lincoln had been Taney's most prominent critic. Taney remained on the Court, but he actions sometimes frustrated Lincoln. After Lincoln suspended the writ of habeas corpus in parts of Maryland, Taney ruled in Ex parte Merryman (1861) that only Congress had the power to take this action. Lincoln ignored the court's order. Lincoln actually issued an arrest warrant for Taney, but the warrant was never carried out. However arrests continued without the opportunity for those arrested to challenge the validity of their arrests using the remedy of habeas corpus. The applicant in that case, Marylander John Merryman, was released to civil authorities and a federal grand jury in Baltimore charged him with treason on July 10, 1861.

Taney spent his final years in poor physical and financial health. His yearly salary remained at approximately $10,000 and he cared for his daughter Ellen, who was also in poor health. Taney died on October 12, 1864, at the age of 87. The next morning, the clerk of the Supreme Court announced that "the great and good Chief Justice is no more." Taney served as chief justice for 28 years, 198 days, the second longest tenure of any chief justice. President Lincoln made no public statement following Taney's death, although Lincoln, Secretary of State William H. Seward, Attorney General Edward Bates, and Postmaster General William Dennison all attended Taney's memorial service in Washington.