The actors – now backed by the MPAA – have testified before a state assembly committee to the harm and risk inflicted on their children by what they perceive as ineffective legislation

Jennifer Garner has joined a bid by the Oscar-winning actor Halle Berry to introduce new laws in California aimed at protecting children from the activities of paparazzi photographers.

The two women appeared before a committee at the state assembly in Sacramento to argue that the offspring of celebrities were not responsible for being born into the public eye and should not face daily harassment by photographers.

"We're moms here who are just trying to protect our children," said Berry. "These are little innocent children who didn't ask to be celebrities. They didn't ask to be thrown into this game and they don't have the wherewithal to process what's happening. We don't have a law in place to protect them from this."

Garner revealed that a stalker who once threatened to murder her unborn child was caught hiding amongst a group of paparazzi outside her children's school. "There are violent, mentally-ill stalkers who can now get close to my kids by simply following mobs of photographers and blending in," she said. "Like the very man who threatened to cut the babies out of my belly. Who was arrested waiting behind our daughter's preschool, standing among the throng of paparazzi. That man is still in prison, but I have no doubt there are others like him still out there."

The star of Juno and Daredevil, who is married to fellow actor and film-maker Ben Affleck, added: "I chose a public life and understand that this means sacrifices in terms of privacy for our jobs. In my case this means that I am sometimes photographed. However my three children are private citizens and more than that – at one, four and seven-years-old – they're just little kids.

"Literally everyday there are as many as 15 cars of photographers waiting outside our home," she said. "In the course of our ordinary day – trips to school, pediatrician, ballet or the grocery store – paparazzi swarm. Large aggressive men swarm us causing a mob scene, yelling, jockeying for a position, crowding around the kids.

"My 17-month-old baby is terrified and cries. My four-year-old says, 'Why do these men never smile? Why do they never go away? Why are they always with us?'"

The proposed measure, titled SB 606, would increase jail and financial penalties for photographers deemed to be harassing children under 16 and make it easier for adults to take out restraining orders. It has now passed the upper legislature of the state assembly and on Tuesday was sent for review before the assembly appropriations committee – moving it one step closer to becoming law.

Film industry body the Motion Picture Association of America is now backing Berry and Garner in their fight after initially hinting at reservations. Both the California Newspaper Publishers' Association and the National Press Photographers Association continue to oppose the measure becoming law.