Ann Arbor's annual celebration of all things cannabis, known as the Hash Bash, returns this Saturday.

Thousands of marijuana advocates from throughout Michigan and beyond are expected to swarm the University of Michigan Diag at noon for a two-hour rally featuring speakers ranging from comedian Tommy Chong to Lansing Mayor Virg Bernero, as well as activist John Sinclair, for whom the original rally was held in 1972.

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The annual event, which organizers call a "speak out and smoke down" protest, has a long history in Ann Arbor, now in its 44th year.

Tommy Chong, Shelby Chong and Cheech Marin at the Michigan Theater on the day of the annual Hash Bash in Ann Arbor in April 2010.

The addition of 76-year-old Chong, of "Cheech and Chong" fame, to this year's lineup is expected to draw a larger crowd than usual.

Serving as the political backdrop for this year's festivities is the prospect of a 2016 ballot initiative to fully legalize marijuana in Michigan, not just for medical purposes.

Representatives from the newly formed Michigan Comprehensive Cannabis Law Reform Initiative Committee will be discussing their plans at the rally.

The group is planning to launch a petition drive this year to put a legalization proposal before Michigan voters in November 2016 to preserve and expand the state's medical marijuana law, create a system for taxation and regulation of marijuana for use by people who are 21 and older, and permit hemp farming.

The group argues that could bring thousands of jobs and hundreds of millions of dollars to Michigan, including new tax revenue for roads and schools.

Recent polling suggests roughly half of Michigan voters support the concept of legalization and taxation of marijuana.

"Some may say Michigan is not ready. To that, I say we've been ready," said Nick Zettell, Hash Bash organizer and a member of the ballot initiative committee.

"We have quite an impressive movement going on here right now, and we're going to really be using Hash Bash to mobilize the attendees and get them to spread the word about the cause and our specific legalization effort."

Zettell said the Hash Bash, the nation's s longest-running marijuana legalization rally, has evolved into more of a political rally than a protest.

State Rep. Jeff Irwin, D-Ann Arbor, is planning to speak about legislation he'll be introducing to legalize marijuana in Michigan. A bill he introduced last session seeking to decriminalize marijuana failed to advance in the Legislature.

Irwin said his new bill incorporates lessons learned from Colorado, which legalized marijuana in 2012.

"I've been talking with a wide range of folks about what should be in the bill and what lessons we can learn from Colorado," Irwin said.

Irwin said he considers Colorado's foray into legalization "mostly successful," but he thinks Michigan can improve upon what Colorado did.

For instance, he believes Colorado set its tax on marijuana too high. He said his bill strives to create a situation so buyers and sellers of marijuana would choose to go the legal route, and not give a big advantage to the black market.

"If we want to have the public safety gains of breaking the black market, taking this power and income away from the black market, and be successful in making sure trade in marijuana is regulated, then we have to create a system where the barriers of entry for people ... are reasonable enough," Irwin said.

Irwin said his bill would allow people to privately grow and smoke marijuana, but it wouldn't allow smoking pot in public. He said it also would allow local communities to decide to ban the sale of marijuana in their communities.

He acknowledges it will be tough to get his legislation through the Legislature, but he said there seems to be growing bipartisan support.

"People are increasing in their support for this for both practical and philosophical reasons," Irwin said. "Legalized marijuana is actually under more control than illegal marijuana, and that's the thing that I think is changing a lot of minds."

In addition to Irwin and Bernero, three other elected officials, including Saginaw County Sheriff William Federspiel, Ann Arbor City Council Member Sabra Briere and state Rep. Mike Callton, R-Nashville, are speaking at Saturday's rally, alongside reform advocates, patients, cancer survivors, veterans and others.

U.S. Rep. Earl Blumenauer, a Democrat from Portland, Oregon, also has prepared a statement to be read at Hash Bash, organizers said.

U-M's Department of Public Safety warns that Hash Bash is not an amnesty day where campus police look the other way on pot smoking on campus. While they allow the rally to happen as a matter of free speech, campus police follow state law and will be making arrests for anyone caught with drugs, including marijuana, on university property.

Elsewhere in Ann Arbor, marijuana has been decriminalized since the 1970s, with the city penalty for possession being a $25 ticket for a first offense.

"U of M is a no-smoking campus," Zettell said of smoking during Hash Bash. "We don't condemn or condone the use, but it is illegal on campus, which is state property, so it's sort of enjoy at your own risk. That being said, the police last year were very accommodating, and we hope to see that continue."

He added, "Above all, we encourage people to be safe and be respectful and just enjoy themselves and listen to what the speakers have to say."

Before the rally on the Diag, organizers plan to hold a protest against federal drug enforcement raids outside the Federal Building at the corner of Liberty Street and Fifth Avenue from 10:30 a.m. to noon on Saturday.

The Monroe Street Fair, a related annual festival surrounding Hash Bash featuring live music and street vendors, starts at 10 a.m. and goes until 6:30 p.m. on Monroe Street between Tappan and Oakland, two blocks south of the Diag. That will be followed by the annual Hash Bash after party at the Blind Pig at 8 p.m.

Ryan Stanton covers the city beat for The Ann Arbor News. Reach him at ryanstanton@mlive.com or 734-623-2529 or follow him on Twitter.