At 4:20 p.m. today, millions of people around the world are expected to congregate in public places and defy laws prohibiting the use of cannabis-based products.

The number of marijuana-related arrests on campus has decreased 20 percent since last year, while the number of marijuana-related referrals has increased, according to USC Dept. of Public Safety Capt. David Carlisle.

Students in possession of one ounce or less of marijuana are referred to the Student Judicial Affairs and Community Standards, while those in possession of more than one ounce of marijuana are arrested.

According to Adam Leventhal, a USC associate professor of preventative medicine and psychology, college students might choose to use marijuana because of a genetic predisposition, the euphoric and calming effects the drug can deliver, or because of the way marijuana is represented in modern society.

Leventhal also said colleges often foster an atmosphere conducive to trying new activities and, subsequently trying new drugs.

“Marijuana is an example of a new experience that people can try for the first time when they are in college, like certain sports or sexual activities,” Leventhal said. “Some students are sensation seekers and thrive on those new, exciting experiences.”

Marijuana has been decriminalized in California since 2010, meaning possession of one ounce or less of marijuana is only punishable by a $100 fine. Possession of more than an ounce of marijuana is a misdemeanor under state law, and results in a $500 fine and up to six months in jail.

Some USC students, including Justin Hunter, a freshman majoring in computer engineering and computer science, believe marijuana should be legalized.

“It is much less harmful than any legal drug such as drinking alcohol or smoking tobacco,” Hunter said. “It is [also] less harmful for the people around the user.”

DPS is not planning to alter its operations or policies today, according to Carlisle.

A study released earlier this month by the Partnership at Drugfree.org in conjunction with the MetLife Foundation reports the number of young adults who admitted to using marijuana increased from 32 percent in 2008 to 39 percent in 2010.

The Youth Risk Behavior Surveillance System under the Centers for Disease Control and Prevention, however, indicates the percent of teenagers using marijuana has not changed from 2007 to 2009. These statistics are more accurate, according to Adam Leventhal, a USC associate professor of preventative medicine and psychology.