Police arrested three people on the University of Colorado campus on Friday afternoon for trespassing during a pot rally that authorities had tried to discourage by laying down fish-based fertilizer.
CU had closed its Boulder campus on Friday to minimize the 4/20 marijuana rally, 9News reported.
The 4/20 rally, which takes place in several locations across the country at 4:20 p.m., has become an opportunity for proponents of marijuana to campaign for its legalization, with CNN noting that one of the biggest gatherings is the smokeout on the CU campus.
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Last year, an estimated 10,000 people came to smoke the weed on the campus' quad.
In Austin, Texas, meantime, country music legend Willie Nelson, who's open about his marijuana use, was scheduled to help unveil an 8-foot statue of himself at 4:20 p.m., local time, NECN reported.
On Friday, police officers were stationed at the entrances to campus to check IDs. The university said it considered those found on campus without a valid ID as trespassers who could face a $750 fine and jail time.
Several protesters have gathered on Farrand Field, but the size of the crowd is a fraction of what has been seen in past years.
The school, determined to prevent a repeat of last year's event, was also shutting the campus to all unauthorized visitors, and offering a free campus concert by hip-hop star Wyclef Jean (WY'-klef zhahn), NECN reported.
On Thursday, a judge ruled CU could keep its campus closed after six residents filed a lawsuit claiming the move violated their First Amendment rights, according to 9 News.
It also applied the fish-based fertilizer to the area of the campus where the marijuana celebration usually took place.
"We're trying to do things to make it not a fun place to be," CNN quoted university spokesman Bronson Hilliard as saying.
"We're telling people they'll have a lot fewer headaches if they stay in Denver."
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