In this Jan. 12, 2012 file photo, inmates walk around a recreation yard at the Deuel Vocational Institution in Tracy, Calif. Credit: Rich Pedroncelli/AP Photo

As many as 30,000 California state prison inmates refused meals for the fourth day to protest rules and policies that they claim are inhumane.

"The CDCR (California Department of Corrections and Rehabilitation) is recklessly placing people in solitary confinement and not following proper procedures at all," Alexis Agathocleous, staff attorney for the Center of Constitutional Rights Agathocleous, told ABCNews.com. "The conditions are exceedingly harsh. Inmates are not allowed to call home at all and not allowed any physical contact with family."

Agathocleous said the inmates are placed in solitary confinement also known as "the SHU" based on evidence of gang association, rather than gang conduct.

"The main issue is long-term solitary confinement," Carol Strickman, staff attorney for Legal Services for Prisoners with Children told ABCNews.com. "Inmates who haven't been found guilty of a violation of a prison rule are placed in solitary confinement for long periods of time merely by association."

CDCR did not respond to requests for comment.

George Ruiz, an inmate in Pelican Bay, was put in the SHU for 22 years allegedly because his name had been on a list of gang members, according to Agathocleous.

The Center of Constitutional Rights accused the CDCR of housing thousands of prisoners like Mr. Ruiz for over the past 30 years, even when they have not engaged in gang related contact.

This isn't the first time inmates have gone on hunger strike. In 2011,state inmates refused meals to seek rule changes and improve solitary confinement conditions. The CDCR made some changes, but the prisoners and advocates for the prisoners rejected them.

"The CDCR doesn't see a problem with their current system or why they should consider changing it," Strickman said. "This time, prisoners are planning to go on much longer. The hope would be that people in California learn about solitary confinement and gain more education on the issue so that they can support change."