A federal judge declared California's death penalty unconstitutional Wednesday, saying delays of 25 years or more in deciding appeals and carrying out occasional executions have created an arbitrary and irrational system that serves no legitimate purpose.

The ruling by U.S. District Judge Cormac Carney of Santa Ana was limited to a single case and had no immediate impact on executions statewide, which have been halted by federal courts since 2006 because of multiple problems in lethal injection procedures.

But if upheld on appeal, the decision would end a California capital punishment system that has been approved by the voters three times - in 1972, 1978 and 2012, when an initiative to abolish the death penalty lost by four percentage points. Despite voter sentiment, the death penalty in California has rarely been implemented in recent decades.

The state has the nation's largest Death Row, with 748 inmates, and its lowest execution rate, with 13 inmates put to death since 1992.

As Carney noted, out of more than 900 convicted murderers sentenced to death since voters passed the current death penalty law in 1978, far more - 93 - have died from illnesses, suicide or other causes than on the executioner's table. An additional 39 have had their sentences reduced by the courts.

Executions 'unlikely'

For most condemned prisoners, "systemic delay has made their execution so unlikely that the death sentence carefully and deliberately imposed by the jury has been quietly transformed into one no rational jury or legislature could ever impose: life in prison, with the remote possibility of death," said Carney, a 2003 appointee of President George W. Bush.

That delay, Carney said, "has resulted in the arbitrary selection of a small handful of individuals for execution."

He said more than 40 percent of the current inmates have been on Death Row for more than 19 years, including Ernest Jones, sentenced to death in 1995 for a rape and murder in Orange County. Jones' lawyers challenged the death penalty system in his appeal, and Carney said his long stay on Death Row was the product of an unconstitutional system.

A statewide order could come from the Ninth U.S. Circuit Court of Appeals, where the state can appeal Carney's ruling. Attorney General Kamala Harris is reviewing the decision, said spokesman Nick Pacilio. There was no comment from Gov. Jerry Brown, who, like Harris, personally opposes the death penalty but defended it in court when he was the state's attorney general.

The issue could then head to the U.S. Supreme Court, which reinstated capital punishment nationwide in 1976 - four years after declaring all state death penalty laws unconstitutional - but in recent years has narrowed its scope somewhat, banning executions of juveniles and the mentally disabled.

"Other states have comparable problems in terms of rarely executing people, and long years of delay," said Richard Dieter, executive director of the Death Penalty Information Center, which opposes capital punishment. "This case has the potential to be a very important one."

3,000 on death row

Out of 18 states that have abolished the death penalty, he said, six - Maryland, New Jersey, New York, New Mexico, Illinois and Connecticut - have done so since 2007, all after long periods with few executions. There were 3,000 prisoners on death row nationwide last year, but 39 executions, Dieter said.

The ruling "further proves that the death penalty is broken beyond repair," said Gil Garcetti, who sought numerous death sentences as Los Angeles County district attorney but joined the 2012 initiative campaign to repeal capital punishment. "It is exorbitantly costly, unfair and serves no legitimate purpose."

Kent Scheidegger, legal director of the pro-death penalty Criminal Justice Legal Foundation, predicted the ruling would be overturned on appeal. Other courts have ruled that long waits on death row are mainly due to inmates' appeals, not constitutional violations by the state, Scheidegger said, and the same holds true in California.

But Carney said the delays in California aren't caused by needless appeals or by the state's legitimate efforts to safeguard defendants' rights, but by the "dysfunctional administration of California's death penalty system."

Inmates sentenced to death must wait three to five years for a court-appointed lawyer and nearly 14 years for the California Supreme Court to make an initial ruling on their case, with further delays in additional appeals to the state and federal courts, Carney said.

"When the state permits the post-conviction review process to become so inordinately and unnecessarily delayed that only an arbitrarily selected few of those sentenced to death are executed, the state's process violates the Eighth Amendment," which bans cruel and unusual punishment, the judge said.

He noted that a statewide commission headed by former Attorney General John Van de Kamp concluded in 2008 that the death-penalty system had broken down and recommended changes that were largely ignored. They included a substantial increase in funding for legal representation.

The last time California's death penalty was struck down was in 1972, when the state Supreme Court ruled that executions were degrading and inhumane and violated the state Constitution. The voters overturned that ruling in November 1972.

2006 moratorium

In 2006, a federal judge in San Jose halted executions statewide after finding that flaws in lethal injection procedures and staff training at San Quentin State Prison created an undue risk of a botched and agonizingly painful execution. The ruling has preserved the lives of 17 inmates who have exhausted all other appeals.

As a result, "we don't have a functioning death penalty in California," said Ellen Kreitzberg, a law professor at Santa Clara University and director of its Death Penalty College, which trains capital defense lawyers. She said Wednesday's ruling could carry additional weight, coming from "a conservative Bush appointee known for harsh sentences."