ATLANTA -

In the last five years, the Georgia Supreme Court has considered eight cases where lower courts threw out a death sentence handed down by a trial jury.

Each time, Georgia's highest court reinstated the original sentence.

That result pleases prosecutors, The Atlanta Journal-Constitution reports. But defense attorneys and capital punishment opponents say it's troubling, particularly in cases where jurors aren't allowed to give a convicted killer's mental health history full consideration.

The cases typically involve a condemned inmate appealing his death sentence by arguing that his lawyer performed below required standards during the sentencing phase, after a jury has already determined a defendant's guilt. Several appeals judges have agreed that an inadequate defense helped prosecutors reach the unanimous jury vote that Georgia law requires for the death penalty.

In most of the cases, the Supreme Court hasn't disagreed that defense lawyers were substandard. But the justices overruled the appeals courts by deciding that poor performance didn't affect jurors' decisions.

Among the rulings overturned by the state Supreme Court, several involved the killer's mental health:

— Judge David Irwin overturned Andrew Cook's death sentence, finding that Cook's attorneys failed to present psychiatric evidence indicating that Cook was mentally ill. Georgia executive Cook in February for the killings of two Mercer University students.

— Judge Michael Clark determined that a more thorough investigation of Donnie Cleveland Lance would have allowed the attorney to inform jurors that the defendant, who killed his ex-girlfriend and her new boyfriend, had been hospitalized for mental illness, in addition to inhaling toxic fumes and ingested gasoline as a child. He'd also been shot in the head, abused alcohol, and suffered from frontal brain damage.

— William David Riley was convicted of killing his three children by burning down his mobile home. Judge Kathlene Gosselin later ruled that he deserved a new trial because Riley's lawyer committed failed to present evidence that Riley suffered from two mental illnesses. Apart from consideration of his mental capacity, the lawyer did not play a recording that would have shown Riley had been ordered to move his car when the home was on fire, a fact that would have countered claims that he chose to move the vehicle rather than rescue his children.

The U.S. Supreme Court, in a 1984 case, set the parameters for how appeals courts must judge the performance of defense attorneys. Georgia State University law professor Anne Emanuel noted that it's the same guidance for the appeals judges as for the state Supreme Court, making such a pronounced trend of reversals unlikely.

"That makes it all the more surprising that in eight cases where trial judges who heard the evidence (and) granted relief, the Georgia Supreme Court reversed them," Emanuel said.

In those reversals, the state's high court has cited other testimony to support its conclusion that a defense attorneys mistakes aren't enough for a new sentencing process. For example, in Lance's case, the justices noted testimony from a jailhouse snitch who told jurors that the convicted killer bragged that hit his former girlfriend "so hard that one of her eyeballs stuck to the wall."

Still, some of the circumstances in the eight appeals are similar to the last case in which the Georgia Supreme Court upheld a state court judge who overturned a death penalty. In that June 2008 ruling, the justices agreed that Mark McPherson, who killed his girlfriend in Floyd County, deserved a new sentencing trial. McPherson had argued on appeal that he may not have been sentenced to death had jurors listened to evidence that he was abused and neglected as a child and went on to an adulthood of substance abuse and mental illness.

He awaits resentencing.