When the Senate voted Tuesday to silence Elizabeth Warren after she read parts of letters from Coretta Scott King and Edward Kennedy in the debate over the confirmation of Senator Jeff Sessions as attorney general, it signaled a return to a notorious history of gagging speech in Congress (“Senate rebukes Warren over Sessions speech,’’ Page A1, Feb. 8).

Warren was following in the path of another great Massachusetts politician, John Quincy Adams. Though a somewhat lackluster president, Adams made his most courageous contribution to US politics after he finished the presidency and served in the House of Representatives, where he was a champion for the antislavery forces.

When petitions in favor of the abolition of slavery poured into Congress, in 1836 the House passed the Pinckney Resolutions, authored by Henry Pinckney of South Carolina, which prevented legislators from reading or discussing antislavery petitions in Congress. Adams led the opposition to the gag rule and eventually secured its repeal in 1844.

How is it possible that, more than 170 years later, Warren is being silenced on the floor of Congress for raising issues about the rights of African-Americans?

Kathryn Sikkink

Cambridge

The writer is a professor of human rights policy at the Kennedy School of Government.