University of Colorado officials hoping to curtail an annual marijuana-smoking gathering say those entering the Boulder campus during this year's 4/20 event must be cleared to do so or will need a university ID. Police have mostly monitored the thousands of attendees at the April 20 event. But this year, checkpoints will be set up at all of the campus' major entrances, and more officers will be on patrol.Those not affiliated with the university and those not attending other events on campus could be ticketed for trespassing, a charge that comes with up to six months and jail and a fine of up to $750. Campus police spokesman Ryan Huff said an estimated 10,000 gathered on campus at 4:20 p.m. on April 20, 2011 to smoke marijuana.(It) doesnt reflect well on the reputation of the University. This is something that has to end. (It) will take some number of years, but wed like to see it go away, Huff said.We feel its important enough to stop this event now before weve got 15 or 20,000 people, CU Boulder spokesman Bronson Hilliard said.The Chancellor decided to close the campus, Hilliard said, invoking a long-standing Campus Use of University Facilities (CUUF) policy, "intended to prevent interference and material and substantial disruption of University functions or activities, promote safety, protect University property and to facilitate scheduling and management of University Facilities and/or Outdoor Spaces."While the policy's been used to close the campus following large weather events, such as blizzards, this is the first time the policy's been invoked to block access to a public event, Hilliard said."Its an important decision and its one weve really thought through. Its not a decision thats made lightly, Hilliard said, noting that instructors and students complained after last year's rally that they were forced to smell marijuana smoke in class for much of the day.Despite taking roughly $60 million dollars in state taxpayer dollars annually, the school's leadership felt blocking public access to the school for one day was warranted.Its theirs (the public's) for all time. We believe were taking a step thats in their interests. Its their children that theyre sending here to learn, not to party in the sunshine on 4/20, Hilliard said, adding that some people climbed large trees last year, leading emergency responders to wonder how they would get through the large crowd to render medical aid if someone was injured.Next week, the Boulder City Council will consider a resolution expressing the citys support for CUs plan.The resolution reads: "Despite the University of Colorado's remarkable success and contributions to the city, state, and nation, substance abuse and highly publicized events that promote illegal activities have challenged its academic reputation and the well-being of the student body, as well as the larger Boulder community.""We are certainly grateful for the resolution," CU spokesman Bronson Hilliard told the Daily Camera. "We've been working with the city and Boulder Valley schools for a healthier and safer community, and drug and alcohol mitigation issues are part of that. All of us agree it is important for the city to come out with supportive statements at important moments, and this is an important moment."Dennis Blewitt of the Boulder Committee to Protect the First Amendment calls CUs plan a threat to the First Amendment.In a statement, Blewitt said the 4/20 event is a protest against marijuana laws.This right to protest is protected by the First Amendment to the US Constitution. The 4/20 protests last less than an hour, and then the 10,000 CU student protesters quickly dispersed. Very few arrests were made and there was no violence or any other trouble on the part of the protesters, Blewitt said.Huff told 7NEWS 23 tickets were issued last year and five arrests were made.The Colorado State Patrol has said they will add patrols around Boulder on 4/20 to help monitor for DUI and DUID drivers.