The Clash of The Titans star had forgotten about the scandal, which took place when he was a student at the University of California in Berkeley 40 years ago - but it almost cost him a job.
Hamlin, who owns property in Canada, admits the incident inspired him to write his new autobiography, Full Frontal Nudity. His arrest mug shot graces the back cover.
He says, "I was going up to Canada to do a job... and I get to the border and they did a 40-year background check on me. Forty years ago I was arrested.
"All they had in the records that I was arrested on a felony charge; it didn't end up being a felony charge.
"They said, 'You're a felon... We have to assume you're a felon, so you have to go through criminal rehab.' I went through a year of criminal rehabilitation, so that I could go to Canada, where I have a home."