LINCOLN, Neb. (AP) — Adult sex trafficking victims who work as prostitutes could get immunity from prosecution under a bill advanced by Nebraska lawmakers.

Senators gave first-round approval to the measure on Wednesday with a 32-0 vote. Nebraska already provides legal immunity to juvenile sex trafficking victims, and the proposal by Sen. Patty Pansing Brooks of Lincoln would extend the protection to adults.

Advocates say current law punishes sex trafficking victims who are controlled or coerced by pimps.

Some senators say they support the bill’s intent, but raised concerns that it could be unconstitutional because it creates a separate class of person who cannot be prosecuted. They also contend that a lack of arrest records makes it harder to track whether a prostitute has been trafficked in other states.