LINCOLN, Neb. (AP) – A legislative committee has advanced a measure to close a 143-year-old loophole in the Nebraska Constitution that allows people to be enslaved as punishment for a crime.

Members of the Judiciary Committee voted 7-0 on Wednesday to send the proposed constitutional amendment to the full Legislature.

The state constitution has banned slavery and involuntary servitude since 1875, except as punishment for a crime. Supporters say that provision hasn’t been used in recent history, but was once invoked to force former slaves back into unpaid labor for private parties, a system known as convict leasing.

The amendment would need support from at least 30 senators before it can appear on the 2020 general election ballot. Voters would then have to approve it.