On January 1, 1831,[3] Loring was one of twelve abolitionists who gathered in the basement of the African Meeting House to found the New England Anti-Slavery Society.

[4] Along with David Lee Child and Samuel Edmund Sewall, Loring frequently provided legal advice to abolitionists.

In 1836, to appease conservatives who were upset by local activists, Massachusetts governor Edward Everett proposed legislation that would have curtailed the free speech of abolitionists.

[1][5] That same year, he and Sewall successfully argued before the Massachusetts Supreme Court in Commonwealth v. Aves that any slave who was brought to a free state by a slaveholder could not be forced to leave.

[9] With Richard Henry Dana Jr., Loring defended Robert Morris, Lewis Hayden, and John J. Smith in connection with the rescue.

Three days later, William Lloyd Garrison and Wendell Phillips eulogized Loring at the New England Anti-Slavery Convention; their remarks were published in the Liberator.

[3] The poet John Greenleaf Whittier wrote a tribute to Loring, addressed to their mutual friend Lydia Maria Child.