File photo of marijuana plants on display for sale at the medical marijuana farmers market at the California Heritage Market in Los Angeles, California, on July 11, 2014. (David McNew/Reuters)

UPDATE, 7:30 p.m.: This post was updated to provide more details on the provisions in the bill.

In what advocates describe as an historic first, a trio of senators plan to unveil a federal medical marijuana bill Tuesday.

The bill, to be introduced by Senators Rand Paul (R-Ky.), Cory Booker (D-N.J.), and Kirsten Gillibrand (D-N.Y.), would end the federal ban on medical marijuana and implement a series of reforms long sought by advocates. They include downgrading its status with the Drug Enforcement Agency from Schedule 1 to Schedule 2, allowing doctors to recommend its use in some cases to veterans, expanding access to researchers and making it easier for banks to provide services to the industry.

[What’s in the historic medical marijuana bill being unveiled on Tuesday]

The Compassionate Access, Research Expansion and Respect States (CARERS) Act would “allow patients, doctors and businesses in states that have already passed medical marijuana laws to participate in those programs without fear of federal prosecution,” according to a joint statement from the senators’ offices. The bill will also “make overdue reforms to ensure patients – including veterans receiving care from VA facilities in states with medical marijuana programs – access the care they need.”

The proposal will be unveiled at a 12:30 p.m. press conference on Tuesday, which will be streamed live here. Patients, their families and advocates will join the senators at the press conference.

The announcement was met with praise by advocates.

“This is a significant step forward when it comes to reforming marijuana laws at the federal level,” Dan Riffle, director of federal policies for the Marijuana Policy Project, said in a statement. “It’s long past time to end the federal ban,” said Michael Collins, policy manager for the Drug Policy Alliance, said in a statement. Both describe the introduction of the bill as a first for the Senate.

[The Republican argument to end marijuana prohibition]

Advocates are riding a wave of success in recent years, with voters in four states — Alaska, Colorado, Oregon and Washington — approving the legalization of the drug for recreational use. The idea has made significant gains in public opinion as well. In December, Congress for the first time in roughly a decade of trying approved an amendment that bars the Justice Department from using its funds to prevent states from implementing their medical marijuana laws — a significant victory for proponents of the practice.

Potential Republican presidential candidates Rand, Sen. Ted Cruz (R-Texas) and former Florida Gov. Jeb Bush (R) have all said they support states’ rights to legalize pot, though they themselves disagree with the policy.

In recent years, several national polls have found majority support for legalizing marijuana. Differences are typically highly split by age — the young tend to disproportionately support such policies.

Medical marijuana has been approved to varying degrees in 23 states and D.C.

[A dozen ways to legalize the marijuana supply chain in any state]