The 'Lethal Weapon' star - who has a problematic legal history, most recently pleading no contest to a misdemeanor battery charge in early 2011 - has been seen at a courtroom in Los Angeles waiting to be called into service.
While there Mel, who was wearing a baseball cap, jeans and a sports jacket, was spotted reading a script, using his cell phone and taking photographs with some women who were also in the room, TMZ.com reports.
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Mel - who has a previous conviction for drink driving - is not the only star to have been recently asked to serve jury duty in California, Guns N' Roses front-man Axl Rose - real name William Bruce Bailey - also took part in a civil trial, serving four days on the legal process earlier this month.
Axl said: "It was relatively painless. I was fortunate that everyone in the courthouse and jurors were all really great, plus I got to see daylight from a different prospect."