The top prosecutor for Utah’s most populous county says he won’t enforce the federal law that seeks to prohibit cannabis use if voters pass a medical marijuana initiative in November.

Sim Gill said he wants to see what Utahns decide for themselves, adding yet another voice to what is turning out to be a contentious campaign involving prominent players.

Gill’s entrance into the fray on Tuesday follows years of his support of a more liberal state law for marijuana that would allow patients with an approved list of conditions to obtain products from the plant if their doctors believe it will help them.

“If the conclusion is for whatever serious illness they have that medical cannabis might be of value to them, who am I as a prosecutor to interfere with a parent or loved one?” Gill told The Salt Lake Tribune on Tuesday. “That ought to be a private decision without the threat of prosecution.”

It also further solidifies the lineup of supporters and opponents of a campaign that will be decided in November, if an attempt to disqualify the initiative fails.

Opponents to the initiative are being led largely by the Utah Medical Association, a political group that represents medical practitioners. Gov. Gary Herbert also said he opposes the measure, saying it would lead to efforts to legalize the plant for all adult use.

Late last month, a Salt Lake City office of the Drug Enforcement Administration joined the UMA, conservative group Utah Eagle Forum and others in forming a political group that will fight the initiative. The LDS Church, the predominant religion in Utah, endorsed the UMA statement against the initiative.

Both campaigns traded tit-for-tat accusations of deceptive campaigning in recent weeks, as opponents embarked on an effort to get voters who signed to put the initiative on the ballot to change their minds and remove their signatures.

Proponents of the ballot measure have called a 2 p.m. news conference at the Capitol to respond.

The Tribune will update this story.