As United States Commissioner of the United States District Court, Loring was responsible for issuing warrants for arrest and ruling in cases under the Fugitive Slave Act of 1850, which was widely opposed in Boston and the North. In 1851, an escaped slave named Thomas Sims was captured in Boston; Loring ordered his return to slavery in the South, as required by the new law. Boston abolitionists were outraged. In 1854, Loring ordered another escaped slave, Anthony Burns, returned to slavery in Virginia. During the prosecution of this case there was an attack on the courthouse in which James Batchelder, a 24-year-old police officer temporarily employed by the United States Marshal, was stabbed to death. Widespread protests marked the trial and its aftermath. President Franklin Pierce felt obliged to send United States troops to ensure that the ruling be carried out. Following the Burns decision, abolitionists led by William Lloyd Garrison and Wendell Phillips agitated for Loring to be removed from his office as probate judge. Forming a Vigilance Committee to monitor judges' activities under the law, they circulated petitions and lobbied against Loring with the Massachusetts legislature. Though he had assisted Burns in his court case, attorney Richard Henry Dana Jr. defended Loring before the legislature. Under pressure from an increasingly antislavery public, the legislature made two unsuccessful attempts to remove Loring from office by passing a in 1855 and 1856. Governor Henry J. Gardner, elected as a candidate of the Know-Nothing Party, declined to remove him. In 1857, after the RepublicanNathaniel Prentice Banks was elected Governor of Massachusetts, the legislature passed another Bill of Address against Loring. The new governor complied and removed Loring from office.
Federal judicial service
Loring was nominated by President James Buchanan on May 3, 1858, to a seat on the Court of Claims vacated by Judge John Gilchrist. He was confirmed by the United States Senate on May 6, 1858, by a vote of 27 to 13, and received his commission the same day. He served as Presiding Judge from 1859 to 1863. His service terminated on December 14, 1877, due to his resignation.
Loring was a fourth great grandson of New England pioneer Thomas Loring. His double cousin, also a lawyer, Charles Greely Loring, defended Thomas Sims in the 1851 action.