Moves to ban US filmgoers from videotaping films inside cinemas have been stepped up by the movie industry.
Suspected offenders in California and Ohio could be subject to citizen's arrest under the latest steps designed to cut film piracy.
Similar laws exist in Michigan, Wisconsin and Pennsylvania, with penalties of heavy fines or jail.
The Motion Picture Association of America said it had acted to combat piracy costing $3.5bn (£1.97bn) a year.
Police say they will respond to calls from cinemas to assist in making the citizen's arrest, if resources permit
Offenders caught during the latest crackdown in Ohio could face six months in jail and a $1,000 (£560) fine. The penalty in Michigan, by contrast, is up to five years in jail and a $250,000 (£140,000) fine.
The MPAA said it planned to lobby at least 12 more states this year for similar legislation.
"Enforcement is always a last resort, but we hope this will be a deterrent," said Vans Stevenson, MPAA senior vice-president.
Critics say the movie industry should be more concerned about illegally copying of films by its own employees.
A recent study by researchers AT&T Labs found that three-quarters of films leaked on the internet came from Hollywood insiders or cinema staff taping films from projection booths.
David Joyce, media analyst with New York-based Guzman & Co, said: "That kind of digital piracy is much more of a threat than someone sneaking in with a video camera."
The MPAA has moved to stop sending preview tapes and DVDs to Oscar judges, although it insists that most pirated films are made from camcorders.
The Electronic Frontier Foundation, a US campaign group, said state laws often ignored traditional "fair use" copying of small portions of films for personal or educational use.