The Michigan Supreme Court said an ordinance at Michigan State University illegally criminalizes free speech.
In a 5-2 decision on Friday, the court threw out the misdemeanor conviction of Jared Rapp, who was an MSU law student in 2008.
Rapp was accused of yelling at a parking-enforcement employee and taking his picture after finding a ticket on his car.
Ricardo Rego felt threatened and summoned campus police.
An MSU ordinance bars people from disrupting the work of campus employees.
But in this case, the Supreme Court said the ordinance goes too far.
Rapp was placed on probation for two years, ordered to perform 80 hours of community service and fined $873.