More than 100 people from the fields of the arts, literature, science and academia signed the declaration for the system, The Hollywood Reporter said Friday.
The signatories joined a group of victims of past press abuse to show support for the system that arose in the wake of the phone-hacking scandal involving News Corp.'s former tabloid The News of the World.
Supporters say the system would protect newspapers from political interference, though others say it doesn't provide enough safeguards, The Hollywood Reporter said.
Signatories believe "a free press is a cornerstone of democracy. It should be fearless in exposing corruption, holding the powerful to account and championing the powerless," the declaration said.
"It has nothing to lose, and can only be enhanced, by acknowledging unethical practice in its midst and acting firmly to ensure it is not repeated," the declaration says. "We also believe that editors and journalists will rise in public esteem when they accept a form of self-regulation that is independently.
"It is our view that this charter safeguards the press from political interference, while also giving vital protection to the vulnerable. That is why we support it and that is why we urge newspaper publishers to embrace it," it continues.