Under the rules issued Monday, the lead lawyer on each side must have at least five years of criminal litigation experience; previously, none was required. Also, judges who might preside over capital cases must attend training seminars every two years.
Also, the lead lawyer on each side must have worked on at least two murder trials, and prosecutors must let defense attorneys know quickly if they intend to seek the death penalty.
The rules take effect in March.
Only a few other states including New York, California and Nevada have written rules spelling out experience and training requirements for attorneys in death penalty cases.
"When Illinois establishes standards like this, I think that it says to other states (that) this is necessary to avoid the kinds of problems that Illinois has had," Jim Coleman, a law professor at Duke University who studied the death penalty for the American Bar Association, said Tuesday.
Gov. George Ryan, a first-term Republican, halted executions indefinitely a year ago after a string of men were released from death row either because they had been wrongly convicted or because they received unfair trials.
Since Illinois reinstated capital punishment in 1977, 12 inmates have been executed while the death sentences of 13 others have been overturned.
In some of those Illinois cases and other death penalty convictions around the country that were overturned, the verdicts were blamed in part on incompetent or inexperienced defense attorneys.
Dudley Sharp, director of death penalty resources for the Houston-based victims advocacy group Justice For All, said Illinois' rules seem fair because they apply to both defense attorneys and prosecutors.
"We want the guilty to be prosecuted, and we want them to be prosecuted constitutionally," Sharp said.
The high court also set new standards for disclosing DNA evidence.
Tonya McClary, program director for the Coalition to Abolish the Death Penalty, said she hopes the new rules will "assure a lot more fairness."
But she and other anti-death penalty advocates are worried that lawmakers might use the new rules as an excuse to try to resume executions in Illinois.
"The fact is that we're kidding ourselves if we think this is going to fix the vast amounts of problems we've seen," said Richard Cunningham, a lawyer for nine men on death row in Illinois.
Cunningham represented Ronald Jones, a former Illinois death row inmate cleared by a DNA test in 1999. He said the new rules do not address key problems in capital cases, including racism, the use of jailhouse nformants and unreliable eyewitness accounts.
Illinois Chief Justice Moses Harrison acknowledged in a statement that the court's ability to change the law is restricted.
"Ultimately, the fate of the state's death penalty statute will be a matter for the General Assembly and the governor to resolve," he said.
By NICOLE ZIEGLER DIZON