Like the children of many affluent evangelical families in Dallas, Elizabeth Carlock Phillips and her younger brother Trey Carlock spent their summers at a Christian sports camp in Missouri. After Mr. Carlock suffered years of sexual abuse by one of the camp’s directors, he reached a financial settlement to compensate him for his trauma, but at a suffocating price: He could never tell anyone about what had happened.

Mr. Carlock, a neuroscience researcher, cycled in and out of more than a dozen hospitals and treatment centers, and tried electroconvulsive therapy. He became increasingly detached from family and friends, and took his own life in August 2019. He was 28.

“Trey told a therapist, ‘They will always control me, and I’ll never be free,’” said Ms. Phillips, who added that the family still had no idea what his nondisclosure agreement had dictated, or what truly had happened to him. “He called his settlement dollars blood money, because taking that money in exchange for an NDA felt like a bribe.”

She added, “He was silenced to his grave.”

Thanks to the efforts of Ms. Phillips and other victims’ relatives, Texas and Missouri are among several states now aiming to ban such nondisclosure agreements in cases of childhood sexual assault.

To critics, the agreements impose a lifetime gag order and deny survivors the ability to heal by sharing their trauma. They also shield perpetrators and the institutions that effectively protect them, allowing abusers to prey upon more unknowing children.