WASHINGTON — The US Supreme Court on Wednesday took up the difficult issue of what to do about unscrupulous prosecutors willing to induce false testimony and hide exculpatory evidence to convict innocent defendants.

At issue in Pottawattamie County v. McGhee is whether two men sent to prison for life are entitled to sue the local prosecutors in Iowa who helped arrange false testimony that led to their wrongful convictions.

Both men served 25 years in prison before being released after investigators discovered the false testimony and uncovered exculpatory evidence never disclosed to defense lawyers.

The high court has long recognized that prosecutors presenting a case at trial enjoy absolute immunity from citizen lawsuits seeking compensation for alleged violations of their constitutional rights.

But the court has also recognized that a prosecutor may not enjoy the protections of absolute immunity when serving not as a trial advocate but as an investigator searching for clues and corroboration that a crime has been committed.

During oral argument on Wednesday, the justices split into three camps. In one camp were Justices Ruth Bader Ginsburg, John Paul Stevens, and Sonia Sotomayor, who appeared primarily concerned with ensuring that victims of such prosecutorial misconduct have a potential remedy through a civil lawsuit.

In another camp were Chief Justice John Roberts and Justice Samuel Alito who appeared primarily concerned with the potentially "chilling impact" on all prosecutors if the court allowed some defendants to file such citizen lawsuits.

In the center were Justices Anthony Kennedy, Stephen Breyer, and Antonin Scalia who appeared to share the concerns of both other camps.

Deputy Solicitor General Neal Katyal, arguing in support of absolute immunity for the two prosecutors, said the government's position was based on important societal concerns that prosecutors feel free to act as vigorous advocates.

"Absolute immunity doesn't exist to protect a few bad apples," Mr. Katyal said. If prosecutors know they may be sued by disgruntled defendants "they will flinch in the performance of their duties."

Paul Clement, a former solicitor general arguing on behalf of the two wrongly-convicted defendants, said the federal appeals court in New York has allowed such citizen lawsuits against prosecutors since 2000. "There has not been a flood of these cases," he said. "There has been a trickle."

Mr. Clement said he had identified 17 cases brought since the 2000 appeals court action.

Chief Justice Roberts said his concerns went beyond just potential litigation. "We are concerned about the chilling effect on the prosecutors," he said.

Stephen Sanders, a Chicago lawyer representing the two former prosecutors, urged the court to maintain an expansive application of absolute immunity for all prosecutors.

He warned that if the high court ruled for the two wrongly-convicted defendants, "it would work a radical change in the law of immunity."

A decision in the case is expected by June 2010.