Feinstein noted that the 1994 ban was challenged repeatedly in federal courts on multiple grounds, including Second Amendment protections, and survived each time.

CNN: STORY HIGHLIGHTS

Agents sent letters criticizing the concept to teachers and school-board members, and one agency hired a lawyer who questioned the process on multiple grounds, prompting the district to retrace some steps, according to Mr. Lloyd and public documents.

WSJ: Teachers' 403(b) Plans See Big Changes