India, Nov. 6 -- California Governor Gavin Newsom has commuted all the death sentences in the state.

In an open letter to justices of the state supreme court Thursday, Newsom ordered that the conviction of 548 inmates on death row will be changed to life imprisonment, marking the largest mass clemency in U.S. history.

Many of the prisoners on death row in the state have more than one felony conviction, and those cases reportedly require approval of the state Supreme Court to resentence to life.

"I respectfully request that the Court issue its recommendation by the end of this year so that I may act before the end of my term," said Newsom, who is scheduled to leave his office in January.

Newsom said he took this action, which is "among t...