Columbia, SC (WLTX) - The former U.S. Attorney for South Carolina is calling for state leaders to let South Carolina voters have a say on whether medical marijuana becomes illegal.

Bill Nettles has written a letter to the heads of both the state's Democratic and Republican parties, asking them to push their membership to put an advisory referendum on the ballot during June's primary election.

"I think it is important that our state Democratic and Republican Parties allow primary voters to be heard on the important issue of legalization of medical marijuana for seriously ill patients in our state."

An advisory referendum isn't binding; instead, it's meant to give legislators a survey of public opinion on an issue.

For the last few legislative sessions, lawmakers have proposed legalizing marijuana for medical purposes. But each year, the measure fails before reaching a final vote.

Currently, Sens. Brad Hutto and Tom Davis are the lead sponsors on a Senate bill to make medical marijuana legal.

Nettles was the U.S. Attorney in the state from 2010-2016, and one of his jobs was to prosecute drug offenders.