The Supreme Court seemed reluctant Monday to allow criminals to ask for a previously offered plea bargain after they've been sentenced, despite the inmates' claim of misconduct by their lawyers including neglecting to tell their clients that a deal had been offered.

Asking judges to go back and figure out on appeal whether a suspect would have taken a plea deal before a trial, whether a judge would have accepted it, whether a prosecutor would have withdrawn it or whether the negotiations would have fallen apart "is simply unworkable," said Justice Anthony Kennedy, who is often a tiebreaker votes on divisive issues.

The high court heard appeals from two different sets of prosecutors who had their cases overturned by appeals courts that said criminals were denied their Sixth Amendment effective "assistance of counsel" because of mistakes during plea negotiations. The Supreme Court has amplified that by saying that "counsel's representation must not fall below an objective standard of reasonableness" and that there must not be "a reasonable probability that, but for counsel's unprofessional errors, the result of the proceedings would have been different."

In the first case, Anthony Cooper's conviction for shooting a woman in the thigh and buttocks after missing a shot to her head was overturned by the 6th U.S. Circuit Court of Appeals in Cincinnati because his lawyer gave him bad advice. His lawyer told him not to take a plea offer that could have had him out of prison in four years, thinking that there could not be a finding that Cooper intended to murder his victim.

But Cooper was convicted of assault with intent to murder and other charges, and he was sentenced to at least 15 years in prison in Michigan.

In the second case, Missouri prosecutors offered Galin Edward Frye two deals, including one that would have had him out in three months, while seeking his conviction for driving while his license was revoked. Frye's lawyer never told him about the offers. Frye pleaded guilty to a felony charge and was sentenced to three years in prison.

Frye appealed, saying his lawyer should have told him about the offers. A Missouri appeals court agreed.

In both cases, the criminals' lawyers are not arguing for new trials, a position the court seemed to agree with. "The remedy of giving a new trial when the person has already had a fair trial makes zero sense," Justice Samuel Alito said.

But Cooper's lawyer, Valerie Newman, said they should have a chance to go back and consider the plea offer. "I'm saying it's unfair to go to trial when your attorney tells you, 'You can't be convicted.'"

"You are saying it's unfair to have a fair trial; isn't that correct?" Kennedy said.

Several justices seemed concerned about how changing the plea system would affect prosecutors and judges. For example, it's easy for a criminal facing a decade in prison to say he would have taken a plea deal for one year after a judge has sentenced him to 10 years in prison, justices noted.

But the negotiations are going on before trial, and by "not accepting it he has a chance of going scot-free" if a jury finds him not guilty, Chief Justice John Roberts said.

After conviction and sentencing, Roberts said, "presumably the defendant will always say, 'I would have taken that deal, because it's better.' So how is a judge supposed to go back and decide whether that's true or not" on appeal?

Justices will rule next year.

The Missouri case is Missouri v. Frye, 10-444 and the Michigan case is Lafler v. Cooper, 10-209.