Byrn was arrested for distributing information about bith control. She was sentenced to 30 days in Blackwell's Island prison. She was jailed at Blackwell Island workhouse on January 22, 1917 for her activism and subsequently went on a hunger strike. Sanger was concerned her sister would die as a result of this hunger strike and Byrne was force fed while serving her sentence after 185 hours without food or water. As historian Jill Lepore reports in "The Secret History of Wonder Woman," Ethel Byrne was the first female political prisoner in the United States to be subjected to force feeding. Mrs. Byrne was prepared to starve herself to death in support of her cause. Her case was the first of a group of cases known as the "Sanger cases" to be brought to trial.