The couple walked to the courthouse surrounded by reporters and cameras when a man appeared to hit Waits on the neck. He was apprehended by security guards.
The alleged attacker was arrested last year, according to TMZ, after walking onto Hilton's property and fighting with her security. The man pled no contest to assault charges and was given three years probation.
"So creepy seeing that guy in court today, it sent shivers down my spine," wrote Hilton on her Twitter account. "psycho intruder just punched Cy in the back of the head as we were walking into the court house."
Police have the man in custody and are investigating, according to The Associated Press.